Yes, there are accepted variant spellings. I use Maredudd, and since I’m doing a lot of the work in Welsh tree that’s the spelling that you see most. But Maredydd shows up a lot. Later, after the Middle Ages, the name would generally be spelled Meredith, and sometimes you see that in the early profiles, but it wasn’t used then.
In general, there are variant spellings for most names in the Middle Ages. The entire concept of “correct” spelling didn’t get invented in England until the 18th century. Before then, people just spelled things the way they sounded, and because of different dialects, words could get spelled in many ways.
Then, when you add in the Welsh spellings of names, and the variants that the English added, trying to make sense of the different sounds, you can find quite a range.
Same thing with Llewelyn. It often appears as Llywelyn. Or Madog, which is also spelled Madoc.
