I would say 'rehearsal' alone is just shorthand for 'rehearsal letter' or 'rehearsal number.' Probably anyone who has played in an ensemble would understand any of those, as well as just 'letter K' or 'number 23,' etc., in context.
The catch is that it's probably hard to find context examples without searching on every number and every letter of the alphabet individually. However, above is at least one thread in the archive as confirmation, and there might be others if anyone could find them.
Or there are certainly plenty of people in the forum who have played or sung in both languages and could add a vote in support.
PS: I'm posting using someone else's computer, because since the new update I can't post using my older browser, and in Safari on a touchscreen I don't see how to get the option to add an additional suggestion. So perhaps the BE speakers could add 'figure' for BE, if there's support for that -- Ecgberht mentioned it in the thread linked above.