Why is the name there? Your Welsh learner is not going to understand that word as a name without a context.
exactly! that's what I've been thinking, I'm learning Norwegian and that hasn't mentioned a name at all. you don't need a name, particularly a welsh one
Am I right in saying that dim is 'not'? I know there are different ways of saying no but so far we have only been taught nac ydw. When we negate a verb we use ddim ('Dw i ddim eisiau afal' for example - I want not an apple) So when do we use dim and when ddim?
Is your question about soft mutation (i.e. when does "dim" become "ddim") or something else?
But even as a reply to thanks? (I mean like "de nada" or "de rien" are used in spanish and French)
No this is not the same as "de rien" in French. It's a response to a question as to whether you want or need something. Eg "Wyt ti eisiau afal? Dim, diolch" (Do you want an apple? No, thanks)
Does this need to be marked incorrectly purely because I didn’t include the comma?
I've never seen Duolingo care about my commas, but I see from your other comment that something else was going wrong.