I had the same problem with Cash. He was Will in my head for months but then I realised I couldn't have a Will with a Grace. This was way before I started writing. To solve the problem I went to behindthename and literally started reading every name out loud until I found the 'cash' sound. Then I thought of Cashel and I just knew it was right.
Maybe try that?
Is this a modern story? Or are we still in the same time period but just with no magic?
Just looking doing a Google search for the most basic 'names meaning beauty' for the girl and there are tons. Names that Mean "Beautiful" Obviously they'd need to be verified.
I like the suggestion of Ophelia and Imogen. It seems to fit (in my mind) how you are describing Beauty.
For Beast, the first name that popped in my mind was Bastian. Basti sounds like how beast is pronounced in Romanian. I don't know if it fits the tone of your story, but Bastian sounds like a regal but reclusive prince that isn't really a monster.
Imogen has the right feel to it, but I honestly just don't like the name. Ophelia's in the same boat, though it is currently the frontrunner in spite of my dislike of the sound.
I went to behind the name too! I found a few, but nothing that really stuck. The name I had picked out originally (Tabitha) didn't have the meaning I wanted/a meaning I felt I could use, and it just doesn't fit her anymore.
Althea maybe? I personally really like Ophelia, but I can understand someone not being as big of a fan. Filomena/Philomena? Rowena? Delfina?Odessa? Acacia? I'm just throwing a bunch out there that struck me as along the same lines as Ophelia, but that may not be the direction you want to go. Maybe something along the lines of a Scarlett, Magdalene, Silvia, Eden? Or are those too contemporary sounding? Thoughts?
For the boys, again I hope this is the right direction to head in- Aurelio, Carnell, Matthias, Eliezer, Desmond?