I don't know if 'Tindalos' was inspired by Tyndarus -- I can easily see Lovecraft, who was v. knowledgeable about classical authors (indeed, something of a prodigy), adapting it -- but this particular contribution to the Cthulhu Mythos came not by Lovecraft himself but his friend Frank Belknap Long in the story of the same name , and I don't know much about Long's erudition (or lack thereof).
If the name Tyndarus* did inspire 'Tindalos', then it fits the pattern whereby Lovecraft seems to have derived the name Nyarlathotep from Dunsany's Mynarthitep (from "The Sorrows of Search", in Time & the Gods ), rather than his taking over a real-world name like Nodens (whom he believed to have been a Titan) or Dagon (a non-classical deity).
On the other hand, anyone who's any good at making up names for imaginary places will inevitably make up some combination that resembles a real-world name, whether they're aware of it or not (there are only so many good combinations of consonants and vowels to go around). So the question becomes is this a name like Kor, which Tolkien borrowed from Haggard and put to his own use, or a name like Gondor, which Tolkien invented but which resembles both Twain's Gondour and the real-world city of Gondar in Ethiopia, neither of which seems to have been Tolkien's model**. I suspect it falls in the latter category, but the possibility of its being Long's actual source seemed interesting enough to be worth sharing.
*rather than from this play, Long cd also have taken it from the rather more famous King Tyndareus, father of Helen of Troy and at least one of the Gemini Twins (Castor and Pollux).
**the name of The Kingdom of Stone was originally Ond, then Ondor, then finally Gondor in Tolkien's successive drafts.