Hi Roster! Thanks for the comments.

Buzz has a lot of meanings - the principal ones are zumbido and zumbar and mezcla de sonidos confuso o poquissimo claro, but there are many other meanings. I was thinking of the confused mixture of sounds when I translated the first line, something like the sound of an orchestra tuning up before a performance, but on a smaller scale (far fewer instruments). It probably isn't a good choice of words. But "rumour" definitely doesn't work here in English, it has only the sense "informaciones no confirmadas y tendenciosas" although a couple of hundred years ago it had other meanings too. If I'd read to the end of the first stanza before translating the first verse I would have chosen "sound".

I'm not sure about timbrel. Heres how I ended up with "kettle drum":

If the Spanish had been "timbales" I would have used "timpani" but the singular "timpano" is obsolete (and was always extremely rare) in English since long ago, and the other singular forms timpan and tympan last meant a percussion instrument in 17th century English and had come to mean a bowed string instrument by mid-19th century (the word had become obsolete, and was re-imported into English from the Irish "tiompan", which was very differentfrom the romance timpan[um]).
I'm not sure that a timbrel is the right instrument - the word is only used to translate the Hebrew "toph" in current English, so it refers to an instrument mentioned in the old testament part of the Bible which I believe was nothing like a Spanish "timbal" - but I could be wrong. because I'm guessing that Spanish timbal is the same as Italian timpano (which is certainly what Collins Spanish to English dictionary thinks, but I don't much trust that dictionary). And anyway, the modern English singluar of "timpani" is "kettledrum".

But now that you've suggested timbrel, I think maybe I should be thinking of a smaller instrument. Maybe "timbal" here means "tamboril" in which case the English could be eiither "tambourine" or "tambor" depending on exacly what a tamboril is - is it an instrument that is shaken as well as struck (tambourine), or is it only struck (tabor)? Tabor is still valid in modern English, although very rare because that instrument is no longer popular. Tambourine on the other hand is going strong - children get to play with it at school at age 6 or so.

cantar - you are the Spanish expert, not me, and I need to undetstand what the word means here in order to pick the right English word (playing, singing , melody, and music are the four most obvious possibilities). Does it refer to the music as performed on the particular occassion, or to the music as it might be expressed in musical notation as an ideal form, without regard to the particular interpretation? "music" probably covers all possibilities, otherwise if it's the ideal, "melody" is the correct translation"; if it's the performance, it's maybe "playing" or "singing" depending on which is the more important aspect of the performance, or if both aspects are equally important maybe it could be "performance" but "performance" sounds horribly wrong to me. Actually, thinking hard about it I reckon "music" is probably best but it does depend on what "cantar" actually means.

I'll try to do something with "Group".

Hi Rosa! Of coure I'm analytic, I trained as a mathematician and my research started out in semantics of mathematical calculi and formal logics, and later I was heavily involed with formal semantics of computer languages and with work on expressiveness in those languages.

What you are saying about "comparsa" makes it sound like something associated with a street party or a carnival, but I think you are saying it's about the atmosphere of such an event rather than any individual troupe or group or act; I've hunted around on the web, found lots of cases where it's translated and doesn't mean that and lots of places where it isn't translated but clearly does mean that, which suggests a difference between formal and informal use. Also cases (again without translation) where it apparently just means a party in the open air, or where it means a carnival. The verses appear to be about something coming from far to near, starting out of sight and getting closer, so perhaps part of a carnival procession, I think, but I'm not sure.

I'll go with your idea of leaving the title in Spanish and adding a note about it.