Relations between the Berbers and Roman Africans were not at all tense, in fact there was a prosperous trade activity and even some population exchange, as there were quite a few Berbers who became rather prominent members of Roman society in Africa.
Nobody said that you didn't have different kinds of relationship, and that this one was only based on warfare : the distinction made between Outer and Inner Mauri can point to a more gradual political and/or social presence in Africa.
But calling these relations "not at all tense" is really puhsing it.
The ethnic distinction in Procopios and critically Corripus on Berbers, accompagnied by a really negative description (such as "savage, violent, britstly, abominable, harsh, cruel, impious, wicked.").
Both authors consider Maur presence as a threat for Africa, when they don't rally to the Empire (opposition Cusina/Antalas but as well Iaudas)
It's interesting to point out that the African Corripus was far more harsh on Berbers that Procopius ever was.
There is also little archaeological evidence for constant raiding in the 4th and 5th centuries, and until the Vandal and Alan invasion, African was widely considered to be the safest province of the Empire
I'm talking about the Vth/VIth centuries there, so I'm not sure what your point is. While there was little raiding (well, except if we consider eastern attacks) with the constitution of Berber kingdoms in Aures or Nemencha, you did have a really important Berber threat on Vandalic Kingdom that culminated with 530's raids and occupation (that wasn't importantly reverted by Byzantines).
As for archeological evidence, the thing is that we have a really important litterary evidence on a generalised Mauri raiding then takeover of Vandalic Africa by the 480's/530's : Procopius, Corripos, local sources... Does these are to be just ignored?
It continued later, while moderated by integration of Inner and Outer Mauri within a regional geopolitical system after than blunt Byzantine tentative to overcome Berber failes (with the Louata's raids, for exemple).
Of course, it doesn't mean that Vandals weren't able to clientelize Maurs, such probably as Cusina; hence the Vandal re-occupation of western North Africa that was largely autonomous on Romano-Berber hands by the 450's/460's.
Hoever, it failed by 484 with the insurrection of Maurs against Vandals and these had to continually fight off them, as Procopius mentions regularly in the
Vandal War.
The Crisis of Vandal Africa (second part of
this part of the study) is probably more complete than what I could tell you there.
The only threat to Roman Africa during the 5th century was the Vandals, and Vandal confiscation of the estates of the wealthy in addition to the central Western Empire shocked by the sudden loss of their wealthiest province was almost certainly was what caused the plea to the Byzantines.
The calling to Byzantines coincides with a period of general takeover and raids of Vandal Africa by Berbers that basically threatened
all the region but coastal parts.
Not that the Carthagian coup didn't coincidate and provided a fair motivation for the war, as it more or less did for Spain; but dismissing out of hand the motivation of Africano-Romans against what looked like a conquest from Mauri would be really strange.