Autocomplete before punctuation. Autocompletion does not work unless the cursor
is at the end of a line or there is a space immediately to its right, so you
cannot put the cursor at the beginning of a word and type a new word using
autocompletion. This is okay except that it does not check for punctuation, so
you cannot put the cursor immediately before a comma, period, colon, etc. and
type a new word using autocompletion. 

Also, autocomplete can suggest a word that starts in English characters but ends
in Japanese kanji characters, but if you are typing in an English font, the
kanji part will show as square error glyphs (corrupted characters known in
Japanese as “bakemoji†because there are no corresponding characters in the
English font). Not technically a bug, although theoretically it should be smart
enough not to do that, especially if you never select its bakemoji suggestion.