I don't think this regular expression does what you think it does. You have not bounded that | term, so it splits your entire regular expression into two. Also you don't need all the stuff at the start since you aren't actually doing anything with it (storing it etc.)
You could achieve your goal with:
/(?:Critical|Minor)\s+(.{0,17})/;
The (?: term groups without creating a back reference. The \s should not use non-greedy matching, using non-greedy matching here will include leading space in the 17 characters if there is more than one space separating the final two fields. Also we want at least one character at that position so + is better than *. The final field needs to be limited to 17 characters, but if there are less, your expression will fail instead of returing as many as it can find.
Nuance