I think you missunderstood me: I would suggest, that you NEVER write “Alpenhorn” in the German instrument list. It should always be “Alphorn”. “Alpenhorn” is not used in Germany. Don’t know why this is used in the English language. Probably a kind of misspelling at some point in history …
Abbreviations is not an easy chapter!
If you look at orchestral scores from the 19. and 20. Centuries from German and Austrian publishers, you will find different spellings and abbreviations. Quite common is to write e.g. “Kontrafagott” and to abbriviate it as “K.-Fag.” but you also could find “Kfg.”. It is not unusual to have instrument names without hyphen and abbreviations which are hyphenated. To come back to your question: “Kb.-Pos.” does make sense, if other instruments are hyphenated too. It looks like modern editions are less hyphenated than older ones. So it would be perhaps a good idea to ask one of the big German publishers (e.g. Schott).
Looking at the other brass abbreviations in Dorico, I want to make some suggestions:
You will find different abbreviations in the literature (Trp., Tromp., Trpt.), but I think the most commen one in Germany is “Trp.”, so I would suggest that.
Here I want to vote for Hr. (H. and Hrn. are other abbreviations, you will find quite often)
Pos. is perfectly fine!
Altposaune should be A.-Pos. (instead of Alt-Pos.) to fit to the other abbreviations for Ternorposaune (T.-Pos.) and Bassposaune (B.-Pos.)
By far the most commen abbreviation for Tuba in German is Tb. (B.-Tb. for Basstuba and Kb.-Tb. for Kontrabasstuba). You can also find different abbreviations here (Btb. or Bßtb., K.-Btb.)
If you decide, to leave out the hyphens in general, than you can always leave out the “.-” in the abbreviation and write the following letter small (e.g. Btb. instead of B.-Tb.).