Origins of Welsh (and/or Brythonic) plural suffixes

[Linguoboy]

This is all very interesting, but isn't it easier to predict the singular using the plural than the reverse? Like with French adjectives?

I don’t think so. Note, for instance, how -a is added to both broad final consonants and to slender consonants with de-slenderising. How would you predict which it was? And going by the model of gadaí-gadaithe, you’d predict *tí for the singular of tithe.

[circeus]

Modern Welsh rejoices in between eight and twenty different methods of plural formation, dependant on the speaker, dialect and analysis. Frankly, this is ridiculous and is more a reason that my native language needs to have a little word with itself than any whingeing about mutation or "not having words for yes and no".

I might have cackled loudly upon reading this XD