G# is a problem for some instruments, such as my Anglo concertina, but one doesn't have to play along with every song.
I generally try to figure out how strong the singer is and what other instruments are chiming in before trying to do accompaniment. Sometimes the accompaniment can be helpful to a singer who does find it difficult to stay in key, assuming the instrument is playing in the key that the singer started in.
It's probably not rude but naive to expect a circle to pick up on a new chorus without repeating it part by part or passing out a songsheet. And even more important to do this with a song where the chorus is different from what people may be familiar with.
I do get impatient with people who always sing from songsheets, week after week, and sometimes with little clue what the melody is. A little homework prior to the song session, circle, can pay off. I like to see people eventually master a song they introduce.