No worries. I honestly think you can make it work by shifting a couple of lines. Since this is a short story, I'd move the reveal of England vs Wales the conqueror a little higher, so we also understand the stakes, and a couple thoughts from the character to help us navigate the language without translation.
I don't think you'd have to reduce the amount of Welsh then. But stuff like 'rhys' room name being followed by something like 'here was the man' s office' or some such in your description of it being a real seat of power, would go a great way towards clearing confusion for me for example.
Honestly if you ever write further inside this world, I'd be keen to beta or read it.
And bear in mind plenty of people weren't that bothered or confused and gave you a vote, so you might want their feedback too!
