Learn English – Are there any words pronounced with an unstressed short monophthong at the end of word that are not /ə/

No, there cannot be. Phonemic /e/ at the end of a word in English can only occur as a phonetic falling diphthong [ej], as in say or they. That’s why those have a ‹y› in our spelling today, and why sleigh has an ‹i› in it.

And unstressed /ɛ/ will soon enough go the way of all things, despite what bokeh enthusiasts would have you believe. (Same with the meh-sayers.) Because English phonotactics forbid an open /ɛ/ at the end of the word, those will therefore soon enough become either a phonemic schwa /ə/ — or else become a close vowel like /e/ or /i/ phonemically and so one with the characteristic falling phonetic diphthong [ej] or [ij] required by English phonotactics.

I therefore little doubt that the word currently spelled bokeh will end up /ˈbokə/ just like the boca heard in the city of Boca Raton, Florida, to rhyme with mocha.

The other two possibilities are for bokeh to wind up rhyming either with hokey or else with hockey. This would be like how Spanish chile which ends with /e/ becomes in English chili which ends in /i/.

Only if the second syllable became stressed could bokeh become /boˈke/ or more likely /bəˈke/, which is the sort of thing you get when in English you pronounce the Spanish word olé under English phonotactic rules.

Whatever happens to words like bokeh as they assimilate to English, they will need to be respelled to use a spelling similar to whatever words they end up rhyming with in order for them to be predictably pronounced by monoglot English readers.

Probably spelling what is now commonly rendered bokeh in English as boka would have been better from the get-go.

Yeah

This is the only word I could think of/find online with the same pronunciation that isn't spelt with an 'r'. There are a lot of different endings with this pronunciation, but this is the only one which ends with "-eah". (There are probably more words with the sound in the middle, but it was harder to search for them.)

Maybe it's not a coincidence that the only word which doesn't have this pronunciation because of a non-rhotic accent is an interjection!