Corrupted crystals are ore that transforms one element into another. Garleans also have teleporters, computers, cameras, cars, a subway, genetic engineering, and robots. It really feels like you're cherry picking here. FF9 ALSO features an inter-dimensional people with advanced technology btw
The hamfisted use of FF9 in this expansion is a whole other discussion I won't be engaging with. To address your Garlean point though yes, they do have those things. They have always been about replicating through magitech what they've been denied. Magic does all of those things, it's established.
Technology doesn't. If you're willing to suspend disbelief for magic oil that lets people zip zap from one place to another and power computers, but some rocks that use lightning to zip zap from one place to another and power computers then your problem isn't with the technology, but the aesthetic
Correct, that is one of the core issues of my problem, it just falls hand in hand with the future-tech aspects. The aesthetic is jarring, too far apart from previously established factors in the game and while that could be considered a narrative tool, it ends up looking like a whole other game.
Sure, but "this last act aesthetic is jarring" is absolutely final fantasy. Like going to the moon, or a floating god island or a futuristic city with space travel or a futuristic city with gene editing, or the inside of an Eldritch monster. You probably had an easier time accepting things as a kid