I have tried a few keyboards on Android. Pretty much any of them that support auto-correct or auto-complete demonstrate backspace issues. Specifically, after auto-correct/complete, a backspace on the word will begin deleting whitespace BEFORE the word as well as at the cursor. Removing the whole word will cause the same behavior on the preceding word.
Discussion
Is anyone working on a fix for open source keyboards? The Samsung and Google keyboards don't have this issue, but you trade privacy.