"Monday I make breakfast."
Translation:Dydd Llun dw i'n gwneud brecwast.
Hmm, interesting. It's quite possible that they're right - I learnt natively as a child so I don't really know any of the rules, just what things should sound like, and saying "ddydd" without anything in front of it sounds weird to me. Either way, you definitely wouldn't be corrected for it in normal speech!