[CovKid66]

Perhaps I'm not up on what the keyboard fixes people are mentioning are supposed to do, but I don't think the OP has an actual problem with his keyboard. The Fn+SYM key combination sounds like it's doing what it's intended to do i.e. pop up the SYM window. It looks like he's try to get it to do more than it was supposed to e.g. press a, followed by Fn+SYM, and have it automatically change the "a" to "á" instead.

Sorry OP, I've not come across that feature before. With so many different variations of the a, e, i, o, etc keys with accents, caret, hats, etc. how would the system decide which one to default to anyway when you pressed Fn+SYM after entering that specifc key?