How do I know if the tag was read OK during a round?

Your phone will vibrate and make a sound. You can turn volume down so that sound does not distract other golfers. 

If using a smartwatch, you will also see the confirmation of the club just scanned and the distance of the previous shot, right on the watch.

Will I get accidental reads? 

No, you need to actually briefly touch the phone with the tag. This virtually eliminates accidental reads.