Or -dur and -der suffixes in general. RG seems to use them interchangeably based on the little data I can find:
Pledari gives "giugadur" as a translation for player, but "giugader da ballape" for football player. The Romansh Wikipedia uses both giugader(s) and giugadur(s) in comparable amounts without a discernible pattern to it.
Are they completely interchangeable, is there a meaning or regional nuance?
Does the same apply to all agent nouns in der/dur?
Also, just to confirm: these words are stressed as giugàder and giugadùr, correct?
Thank you!
The stress is like that, as you say.
I don't know about the usage in RG, but principally, these suffixes are perfectly equivalent in meaning and any difference in their distribution (in all idioms generally) goes either along regional/dialectal lines or according to grammatical rules.
Historically, the -àder continues a Latin nominative -ātōr and the -adùr an Latin accusative in -ātōrem. In the early Middle Age, Rumantsch still had a case distinction.
Hence, some idioms (not sure which) would use something like giugader in the singular from iucātōr but giugadurs/giugaduors in the plural from iucatōrēs.
Ladin Vallader has -tur/-tuors for sg./pl.
Yes, for that reason I was expecting/hoping -ader to be more common in the singular and -adurs in the plural, but that doesn't seem to be the case when looking at the (admittedly limited) Romansh wiki. There isn't a single page where giugadur(s) and giugader(s) coexist; I would need to make a more thorough analysis of the dur/der suffix in general, but that's not so trivially done.
Still, the deeper I go into Romansh the more I find it has many interesting features and is critically underdiscussed.