I'm trying to find and select an entire line where an end nested style marker is found. ~h.+$ will return me everything after the marker, and I can get everything up to the marker with ^.*?(~h) but I can't seem to combine the two. Any help would be appreciated.
I don't think those two queries are doing quite what you think. ^ is the beginning of paragraph marker, and $ is the end of paragraph marker, so you aren't selecting only a single line unless there is only one line in the paragraph.
^.*~h.*$ will find an entire paragraph that has at least one end nested style marker in it, regardless of where it is in the paragraph, but I don't believe there is any way to work line by line.