I know that pedal retakes are not possible for sostenuto, etc., but they seem also not to be possible for the pedal used on a vibraphone (as found in the percussion techniques list). Am I missing something?
No, you’re not, but perhaps you can repurpose the regular piano sustain pedal marking, and override the symbol at the start as needed (or indeed set the Engraving Options for pedal lines such that they use the “Ped.” text by default)?
OK, I’ll do that, thanks. I see now that it’s easy to select all the pedal markings on the vibraphone staff after the fact and use the properties panel to set them to text “Ped.”