Hi Gianfranco,
Oh my, yes, it seems I forgot to add the new pipewire -dev package to the fluidsynth -dev package. 'not sure how that happened, but my mistake! Isn't only waiting 48h a bit rushed for an NMU though? I can of course import your fix and upload in the next 48h, and I'd like to improve your changelog entry, because I think you'll agree that the concept of "runtime" doesn't make sense for headers ;) If this is truly 0-day urgent, I'm confident a team member (IIRC Josch is a multimedia-team member) will upload.
Cheers,
Nicholas
('hope this isn't HTML email, since I'm currently AFK on a phone)