Clever idea, and a great use of crossovers. I caught on to the numbers theme fairly early on, but managed to not get a single group. Well done.

Baffling but entertaining. Must've been tricky to avoid alternative solutions. I amused myself by looking for one and... two is a one-digit prime while the phoneme /h/ isn't pronouned in "three". But what the hell. Cheers.

It was indeed fairly tricky but you can go group by group. There are only 4 clues that fit "3" [I don't think I agree with your alternate: "three" is not pronounced like "tree" - cf "two", or "guild", or arguably "chord"... - but apologies if that caused unintended frustration :-)]. There are also 4 clues that _only_ fit 1. That left the other 2.

It's much harder avoiding alternates if you have shadow groups.

Not frustrating. I was nowhere near solving it. And you're probably right.

Too frustrating to be enjoyable for me :(

There are four one digit primes: 2,3,5,7