Yeah, this is tricky. I still think your best answer is to wait for me to implement a proper xml/html parser for sidecars, or do the parsing yourself in an external script (e.g. with python) and then convert your html into nicer .txt files that hydrus can suck up easier. You could also filter your undesired tags better there.

If the 'description' string is always in the same location, and that location is always the first or last index of your list of strings, then the 'string selector' might help. It does list slicing like in programming, if you are familiar, like "my_list[4:6]". If you aren't familiar with that, or the description is in the middle of the list here, you are correct in trying a string match, which is basically a filter.

If the description line has a classname in the html, you might be able to exclude it with a string match before you Split/Convert all the html garbage away.

I am not totally sure what you mean by being unable to import by pngs, but if I click 'import->from pngs' (pic related is from the 'sidecars' tab of the 'add tags/urls with the import' dialog after you drop some files on the client), I get a file dialog that allows me to import a png like this. Do you get different?