>Why didn’t God send his prophets to multiple regions around the world instead of just focusing on one specific region in the Middle East? I feel like this would have had multiple advantages
There are some who say he did, but that they were misinterpreted.
Some examples are the Dacian prophet Zalmoxis who was supposed to have been a student of Pythagoras who preached about resurrection and life after death, but was later deified and had his doctrine changed into one of eternal return/reincarnation, and also the anonymous prophets of India and the celtic lands who had revelations of trinitarian deities.
Aristotle, Heraclitus and Plato were considered to be prophets, with the latter famously called "Greek Moses" because of how similar his philosophy was with what is in the Pentateuch.
Virgil was considered in Christendom as being a prophet as he wrote (obscurely) in one of his ecloques (number 4) about how a maiden would give birth to a king and a new era would begin
Lao Tsi and Taoism have some similarities with the Gospel too.
>Universalism/Perennialism kinda solves the issue
It doesn't, not because the revelations are "contradictory" (which is man's error of understanding, not God's), but because these deny both a personal God, and that such divine knowledge/sophia can ever really be understood by or revealed to man.