Breton and Welsh in the Kernowek language, help

Hi, for some reason, the Kernowek language on Wikipedia's various interfaces has become flooded with rogue translations into Welsh and Breton. Most Cornish speakers do not speak and cannot understand Welsh or Breton! How can this be fixed, please? Thank you.

Could you give 2 or 3 examples please? I do not speak one of these 3 languages so it is very hard for me to find examples.

Maybe it is a result of more translations for Welsh and Breton in the last time. Since ages these languages are fallback languages to Kernowek in case of missing translations, see https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/core/+/master/languages/messages/MessagesKw.php#18

This could be fixed with removing the fallback chain.

Here a couple of screenshots. I've circled Breton in red and Welsh in yellow.

From what I've read (I am not a very experienced editor), I think you might be right about it being fallback languages. Welsh and Breton are not good fallbacks for Cornish speakers as the languages aren't similar enough to Cornish for Cornish speakers to understand. (I speak Welsh, so I can cope with that, but I don't think all that many can! I don't speak Breton and so I have very little idea what on earth is going on when I see it. To give you an idea, the only words I can work out in the second picture are "pajenn", "gwelet" and "ezhomm", which means I'm pretty clueless!)

On the other hand, I have not yet met a Cornish speaker (and I know many many Cornish speakers) who are not fluent in English, so I'd suggest using that as a fallback language.

I am definitely up for doing some translating into Cornish here to help Cornish get its interface in its own language! I currently mostly use Cornish Wikipedia to use the translation feature to translate articles into Cornish, so for me that'd be a good place to start. But I'm new to translating the interface itself, so I wonder if you could point me to the right section to get started doing that? Thank you so much for your help!

Thank you for the screenshots. I checked a few of the marked translations and can confirm, that these are shown due to the language fallback chain.

I opened https://phabricator.wikimedia.org/T256097 to allow a wider discussion and preparation of a patch.

No problem, I sent a patch to remove it.

They were already configured as fallback for Cornish on translatewiki, and I was just cleaning up configuration by moving some common things from translatewiki configuration to core configuration. I removed it from both now. It will take a few days until it's fully deployed on the Cornish Wikipedia.

Thank you both very much for your help! <3