In my country Latvia - to get further at Eurovisio it is no chance for rock, metal, jazz, latin. Only perfectly balanced pop, soul or disco with superbably writen words that slime together in each part. No other way, believe me i have tried a lot.
This is not about do You learn that You need or don't - some chords on paper. I think there is nothing wrong with that when You have an 3 hour gig or first time rehearsal with a pro band. I always use those notes about songs to be better even if i know the song allready completly. This guy who came empty could easaly hear those 4 songs and write down the chords and some nuances and it would be OK. But he didn't spent an hour and choose to drink a lot of bear and watch some soccer match.
On one side, yes - You could leave now with a simple msg. On the other side - think, do You really like to play with them, had they listened to Your opinion for some times. Finally - we can not give You a complete answer for 100%. You must decide Yourself !