Hey @TCat, thanks for reporting this one. To make sure I'm understanding correctly, you want bookmarks search to search for a string with embedded punctuation in the URL (or even the name) of the bookmark.
So for instance, q=%s&tbs=qdr:y4 in your case should filter the Google 4-Year Search bookmark.
I tested this out and it seems to be working for me. In my screenshot, a search query of K_ID=IC&IT is correctly returning a bookmark with its url containing that string.

If you could provide more details about how exactly to reproduce the bug, it'd be great. Thanks!