I have had this happen. Mostly with weird, old, or cheap (or some combination thereof) hardware. Like sometimes the connection will hitch for a moment then three or four letters will come out backwards. Couldn’t say for sure what the cause is but I suspect either the controller in the board itself is jank, or there’s some kind of protocol / buffer mismatch. I have no solution, but it’s not just you.
.mod files for music. 3-5mins+ of music a piece with a storage footprint in the KB range. Mostly free, tons available online. Check out Mod archive for an easy web interface or ZXTune if you’re on android.