Oh I think I was misinterpreting the issue... do you mean that when a tag like <<set $var to value>> has a period in it, parsing fails? Or is a string with "." in it being considered the end of a section of text, requiring player input afterwards?
The default parser shouldn't be breaking up passages by periods at all, only with linebreaks (and special strings interpreted as linebreaks, as seen here:)
So... make sure that "." isn't in that array! But if that's not the issue, I'll have to take a deeper dive into what may be causing this...