You are correct that the first period is not necessary, that the period in the character set should be escaped, and that the second * should be a +. My regex is a little rusty.
The first * should also be a +, as I want it to match one or more spaces, so the regex should probably be
: +([[:alnum:];.]+)n
The issue I reported with only a single match being highlighted is still present, even with the updated regex.