Re: bookmarks - this should be fixed, but you might have to unbookmark fandoms before rebookmarking them if the bug previously let fandoms "travel" across exchanges. Give the app a refresh and let me know if that works out for you!

Re: requests for single fandom across all exchanges - alas, no. The Filter search box on the Grouped Requests tab doesn't clear out when you change exchanges via the dropdown, so that's the poor man's version way of doing it right now. I think at the end of the year I'll make a 2021 version that combines everything scraped in this past year into a megasearchable version :)