So is a lot of bitcoin gold being received erroneously by recipients then? I have not heard about anyone waiting to make bitcoin or bitcoin cash transactions because of the effect on bitcoin gold (until they implement replay protection).
Not necessarily. After the fork, send the BTG to an address that you control and spend the coins on the Bitcoin chain after. If the transaction on BTG chain is confirmed, they cannot execute a replay attack, no matter what.
Did the replay protection for bitcoin cash go bi-directionally? So that any coins sent on either of the 2 chains will not affect the other?
I'm not sure. Bitcoin Cash does have a different sighashing algorithm from Bitcoin. If BTG follows the sighash algorithm from Bitcoin, then yes, its protected.
How could I check if any BTC/BCH I sent could be claimed as BTG by those recipients?
Check their address. The replay attack can be done anytime as long as the transaction is valid.