Not really enough information to provide much in the way of useful feedback. EGT spreads don’t really mean that much because probe placement can make a huge difference. What matters is, at a given power setting, what fuel flow each EGT reaches peak temperature. Start well rich of peak and gradually lean and watch each EGT, noting the exact fuel flow where each cylinder peaks. The fuel flow difference between the first and last cylinders to peak is a useful basis for comparison if troubleshooting fuel/air ratio issue. The specific temperature values are less useful.
As for your carb heat on/off observation, when carb heat is on the mixture is richer than with it off. If cycling the carb heat doesn’t return EGTs to their original temperatures that indicates you aren’t returning to the previous F/A ratios (either that or your power settings have changed). Perhaps after cycling the carb heat the damper isn’t fully closing and you are getting a bit of warmer air and richer mixture as a result? Just a wild ass guess but verifiable if you have a carb temperature probe.
Keep us posted what you come up with.