Ideally you'll never see bubbles in the beer lines, as they're indicative of CO2 breakout (not "air").
One thing that can cause that is too little CO2 pressure being applied vs the actual carbonation level of the beer.
Eg: if you carbed the beer to 2.5 volumes but set your dispensing pressure too low to maintain that level, CO2 will leave the beer, and the only way out is through the beer line.
It's undeniable physics, so matching the dispensing temperature/CO2 pressure combination to the carbonation of the beer is of primary import.
Another cause of bubbles in the beer line is a damaged or missing O-ring under the Out dip tube flange. If that small O-ring isn't perfect it can allow CO2 from the keg head space to be injected into the beer stream at the Out post. They can fail to varying degree - it's not binary mode (unless it's missing) - so inspection is worthwhile when battling dispensing issues.
As for "once the foam settles the beer doesn’t seem overcarbonated", you're losing the carbonation to foam, so for sure it's not going to appear overcarbonated any longer if it ever was...
Cheers!