Nice! The preliminary filter support in @gotosocial 0.15.0-rc1 can be managed in Semaphore, and works in Semaphone and Tusky timelines.
Unfortunately: Tusky can’t manage the filters, and both clients treat them as hide completely (without the option to use a warning instead), but I suspect that’s because GTS has only implemented version 1 of the api so far.
Also: Elk doesn’t seem to support filters on GTS accounts at all, though it can handle filters on Mastodon accounts. I wonder if it’s also the api level, or if there’s another issue going on with it.