Hi,
I’ve done some digging and it looks like suggestions that begin with a number are not recorded for the spelling-based suggestions and this appears to be because the spelling suggestion system probably doesn’t record any spelling suggestions that begin with a number.
I have raised this with the developers but in the short term there is probably not much you can do about this. The CSV based suggestions do seem to respect triggers that start with a number. As a workaround you could possibly generate a CSV style auto-completion source and use this in addition to or instead of the spelling based suggestions or you might be able to create a spelling whitelist that has some of the suggestions that begin with a number.