Not all the Hobbit-names have been translated of course, but Tolkien did note that he altered the masculine -a to -o, thus Bilba should be the real Westron name of Bilbo (along with Maura if the draft texts are raised).
With Frodo Tolkien goes that extra mile again.
'Frodo is a real name from the Germanic tradition. It's Old English form was Fróda. Its obvious connection is with the old word fród meaning etymologically 'wise by experience', but it had mythological connexions with legends of the Golden Age in the North.' JRRT, 1955 letter to Richard Jeffery
So, could a person who lived many years before Old English arose in the world have a name *Froda? Possible. Would it have a meaning connected to 'experience wisdom'... ah
possible again, but
Orthanc was already a bit too convenient, though fun. Tolkien already had to explain the name Gandalf, or the Dwarf-names, as translations, why not some of the Hobbits too. And this really took off in other ways, for if one used English to translate Westron then one could use other Primary World languages to represent internal languages actually spoken in Frodo's day.
There was no one named
Éowyn, Éomer, and no Rohir spoke Old English, and I think Tolkien enjoyed this conceit of translation, adding to the impression of reality (and explaining certain questions that might be raised by Readers), giving these Primary World tongues a part to play, and giving him some word-play at the same time.
Note that in the drafts it is explained that there was no word
maur- in contemporary Westron, but in the archaic language of the Rohirrim it meant 'wise, experienced'.