Would this be precisely the same if I think they still ARE nice?
The "best" translation is currently "I think that they are nice".
So apparently yes.
Ah, when I answered it yesterday, it did not allow "I think that they are nice," but required "I think that they were nice." Maybe I had some typo I did not notice.
Should there be a wedi in this sentence to indicate they were ie Dw i'n meddwl bod nhw wedi braf?