Was that 1000 test flights, or 1000 tests? The difference is important - using the weapon release clamps to drop a similarly shaped mass would count as a test, and is an important part of developing the system, but is certainly not a complete system test.
Secondly, I'm a bit wary of saying that a single weapon like this will change the course of the war. There have been weapons like that, but they're few and far between - I'm thinking of things like the introduction of stirrups, gunpowder, the internal combustion engine and nuclear weapons as the best examples. By comparison homing torpedoes didn't change the balance of the battle of the Atlantic, and seems like a relevantly similar development.
Taking a step back from the tactical use of the weapon, this technology does not seem to change the higher-level dimensions of the situation a great deal. Ships were still vulnerable to aircraft without it, so there's no major change there - both torpedoes and dive bombers could sink ships. The best way to defend against those threats is the same as this one; don't let the launch platform get within a few miles. It also makes the launch platform more vulnerable, since even after weapon release it has to fly a stable, predictable flightpath while the weapon is guided to its target. If you look up the sort of countermeasures that are used against MCLOS ATGM systems, you'll see what sort of things the Allies could do about them.
I agree that upon introduction they would be surprise, and perhaps have a significant impact in one or two battles. But overall, I doubt that they would have a huge impact. What they could do would be make precision bombing raids against stationary targets much more effective, but the Axis powers weren't really doing a great deal of that.
The source stated weapons tests, but provided not details besides saying they had tested up to 5000 pound weapons systems with 2000 pound warheads. Some of the test worked at the 5 mile range, 10K elevation. I have not yet found more detailed information on the tests. There is a good chance the records are only in German or they were destroyed in WW2. A huge amount of WW2 records were lost as the Russians over ran East Prussia, which appears to have a been a major archive location of WW1 records. Not to mention the Allied bombing campaigns. The source was pretty clear they had the weapon system to operation status. I have not found a source showing it was used in combat, so it likely had some additional issues, missed, or sank something unimportant with few survivors.
After the war, the program appears to have been completely shut down and abandoned. Each of the new programs in WW2 appear to have been started without knowledge or help from this program. There is a complete 18 year gap without funding or R&D. This is not uncommon after WW1. Everyone was so broke that many technologies have 10+ year funding gaps. Radar, applied nuclear physics (partial gap), hardened armor plate for BB, etc. Even the ones that were funding had lower levels than prewar.
I gave a long two post where I explained how the war would play out using the thread authors scenario. You statement is substantially different from the detailed analysis I gave, so I will regive, but have the Japanese use OTL WarPlan to make the changes more obvious, and try to be briefer.
The weapon is likely assigned mostly to the Nell/Betty squadrons. Pearl is the same. It is likely used on the Repulse & PoW, but it changes little in the battle. It is likely meaning a higher loss of smaller ships, but unless you are a true WW2 Pacific buff, you likely don't notice the difference for the first few months of the war. Japan is on such a shoe string logistical budget, little goes better than OTL. Maybe a few Islands are taken a few days or weeks later. Basically, if we were using old percentile dice, Japan was always rolling in the 90's with a lot of 00.
Now lets take the Enterprise. Halsey was quite active with this ship. He was attacked by Nell/Betty on multiple occasions, they just missed. On on attack from memory, it was about 12 planes attacked and caught him with limited CAP. Several were shot down, but at least 6 escaped. One almost Kamikaze onto the deck missing by feet. The flew directly over the carrier and just missed with gravity bombs. About 1000 feet above. If these planes had been carry the glide bombs, we are talking 1-3 hits if we assume the Cap/AA is the same effectiveness. If we assume the greater stand off range reduces losses we are talking 2-6 hits. The Enterprise was not doing major air operation, but did have a few planes setting on the deck with fuel and at least gun ammo. This give us a damaged or sunk carrier, depending on damage control and how large we assume the bombs are. There are a lot of other little battles like this. The USN was spread thin. A better weapon likely leads to more USN capital ship losses.
Now why is this important? Because just like Japan, the USN was on a shoe string budget early in the war. And once we get to Coral Sea time frame, things broke our way. So lets look at what a sunk Enterprise means. Cancel Doolittle raid. One less ship at Midway even if we allow the raid to go on.
Or take the Coral Sea. The Yorktown barely made it out. Probably one more hit means it does not make it home, and if they have a few of these aircraft on the Japanese carrier (torp bombers carrying glide bombs) we see a different Midway. Now these battles can be played out a lot of different ways, but likely the USN is down 1-2 carriers by August 1942. In 1944, it would not matter that much if the USN loses a few more carriers. But with so few ships, the impact is huge. We likely cancel the Solomon's campaign as we know it. Or if approved, it goes much worse for the USA. And Japan new they had an airbase issue in the South Pacific, and were working to cure the problem. Now you can get a war of the same length or a longer war, but it is hard to get a negotiate peace because of Pearl. Not impossible, but hard.
Now as to why this had a big impact and made peace possible in the previous reply was the thread author gave two PODs. No surprise attack and this POD which means 1942 is a win year for Japan, and quite likely a large share of 1943. We then get into the political dynamic of how the USA handles a war that is longer and other butterflies. There was also a third possible POD where there is a decisive battle at sea. In many ways, the USA was fortunate the ships were sunk in harbor. If sunk at sea instead of Pearl, they are not refloatted, and the death toll could climb over 10K. And we did not lose the carriers, which will likely be lost faster with these 2.5 POD's. The interaction of these POD's would give you anything from WW2 ending on the same day as OTL to a negotiated peace, depending upon the butterflies.
Note: You can get the same impact with the prewar development of the Ohka, and this is probably more likely than this POD. But the thread asked for glide bombs, which I interpreted as non-suicide weapons