Hi! New user here, really liking the look of this community with so much friendliness and initiative on display!
I’ve just finished reading Y Byw sy’n Cysgu and have a few questions about unfamiliar things I met on the way. The question is the same with all four quotations: assuming I’m understanding the meaning correctly, is this fine to use today, or is it old-fashioned, or overly formal, or tricky in other mysterious ways? 
- “Gwyddai amcan beth i’w ddweud”
“She knew roughly what to say” (?)
- “doedd gynni hi ddim gwynt iti ddwad”
“She didn’t really want you to come” (?)
- “…heb iddi ddweud wrthi ddarfod i Iolo fod yno” and “Llawenhâi ddarfod iddi allu dweud hynyna”
“…without telling her that Iolo had been there” and “She was delighted that she had been able to say that”.
This question is about darfod. I’ve seen it used like this quite often in older books. It doesn’t look like it’s adding meaning, and we could remove it from both these examples. Just old-fashioned?
- “Mae hi’n braf yma rhagor nag yn y tŷ.”
“It’s nicer here than in the house.”
This one is interesting. It surely means the same as “Mae hi’n brafiach yma nag yn y tŷ.”, just old-fashioned or dialectal?
I’d be most grateful for any comments! Do let me know if this should be in a sub-forum, or whether it’s preferred to split a post like this into separate questions.