I’m curious if the thing with the electric fence is a strange stereotype.
Everything else seems to fit for a horse that’s been very over faced because you’ve been reading her false bravado as understanding & confidence, and she learned along the way somewhere that she can’t say no when she’s being handled directly.
It’s a big task to go back and build all that, especially when she’s afraid but without much of a tell in hand. Doesn’t sound like that’s something you’re interested in, but she’ll make a great horse for someone who is! How kind of her to be so willing, even when she’s so afraid.