Space in automatic pronunciation is unidentifiable in regex

[Floverale-Hellewen]

Hey there,
I know this project has been on hold for some time, but maybe someone can help me out.

Earlier there was a request to add spaces in automatically generated pronunciation (#630). I came to an issue connected to these spaces, specifically, I cannot "catch" these spaces with regex.
More details: using regex in phonology, I'm trying to achieve a change in pronunciation of one of the certain letters at the beginning of a word with the condition that the previous word ends with one of the other certain letters. Simple expressions like (?<=[ei][^\w])([ao]) or (?<=[ei] )([ao]) work everywhere but not in PolyGlot itself. For some reason, the space between input words cannot be found by Unicode space characters, literal space character or \s, \W and ^\w.

I am no programmer and literally just started acknowledging myself with regex, as I am happy to find this lovely program and wish to use all its potential in automatization. So I'm a little at a loss and cannot find a workaround to that. Condition of pronunciation change if a vowel is at the beginning of a word can be achieved with (?<!(\w))([ao]), but then it does not account for a vowel at the end of the previous word :(