It's slightly unfortunate that there are two Spanish examples (BREADPAN being the second) instead of using four different languages, but hey, I'm not the one attempting to create a puzzle worthy of being published in the NYT, so who am I to nitpick? ("Well, actually...")
GUESTHOST is an amazing example. The Slavic languages are so often spelled with incredible combinations of consonants that it's a wonder that anything would work out this way. FIREBRAND is somewhat less surprising, as Dutch and English are so closely related. As I am sure Horace and Frances could tell you in much more detail, seeing as how they've mastered the language for their multiple trips to the Low Countries. THEDIE is amusing in its brevity.
|MELON without its rind|
The rest of the puzzle is smoothly constructed. I am impressed that Mr. Tuffs was able to fit CTHULHU into a grid. And apologies for those unfamiliar with Mr. Lovecraft's oeuvre. His New England roots are deep, and it should also be acknowledged that he had seriously troubling views on race, especially viewed through today's lens.
25A: Competitor with variable skills? (MATHLETE) is very nicely done. I also chuckled at 28D: Preceder of cuatro or chic? (TRES) - the reparsing in different languages fits well with the theme of the puzzle as a whole.
Odd that there are two QMCs which turn on using "number" to mean a musical piece. After getting SOLI, I balked at putting SONGS in for a moment due to the repetition of the concept.
Overall I enjoyed the puzzle, but I do like a Thursday to be more tricksy.