MODIFIER LETTER PRIME not a letter

[snomos]

Reported by @Trondtr:

sms mobile keyboar, android.
Tested on Samsung S7 Edge, Android 8.0.0, Samsung's own Notepad program, with the sms keyboard of 31.1.2019.

PROBLEM:
The keyboard recognises MODIFIER LETTER PRIME but is not able to suggest it.

To repeat:
Open the sms keyboard for android and write e.g.

anteʹnn

The keyboard will display
anteeʹnn anteʹnn anteʹnn

So far so good.
But then I click on the word
anteʹnn

What then happens is that only the part "ante" is underlied, and I get the suggestions
aktt snt ahnte
(all three related to a situation where input is "ante" and not "anteʹnn"

Similarily, if i write anteʹnnn
the program is not able to correct it, since it sees it as two words.

The letter in question, MODIFIER LETTER PRIME, position D12 on the sms keyboard, is a letter according to Unicode, but unfortunately a delimiter according to Android.