Overthrow Rule

[tzme415]

ASA SP 12" Men
R1 on 2nd
R2 on 1st
Batter hits slow roller between Home and 3rd - F1 fields ball and overthrows 3rd - The ball bounces off F5 and ends up going out of play about 50 feet away (F1 really threw it hard for such a short throw)- This field only has fences that extend about 20 feet beyond the bases, anything outside the fence is out of play
I am only ump
I award R1 and R2 home and BR 3rd
Defense Captain comes to me and asks if I saw R2 touch 2nd before the throw, which of course I could not since I was watching the play. The rule is 2 bases from the last base touched at the time of the throw. So I put R2 back on 3rd and BR on 2nd.

Of course, now offensive captain goes wild. I explain call and it quiets. Next batter gets hit that scores both R2 and previous BR, so point is moot.

1) Did I get the call right in the end?
2) Should I have just left the call the way I had it, even if I wasn't sure it was right?