Should AES-CMAC key cryptoperiod be affected by MAC truncation to avoid birthday-attacks?
Yes, truncated MACs influence the cryptoperiod.

First of all, I cannot really think of any case where it makes sense to assume that the attacker only sees a truncation of the MAC if that isn't what is actually used in the system!
And if you actually truncate your MACs to 30 bits you will probably have collisions after $2^{15}$ message blocks. So you definitely need to reduce the cryptoperiod.

On the other hand you're saying an attacker can only see 30 bits of the MAC because you are truncating it. Let us assume that you are still using the full MAC and that this makes sense in your scenario for some reason.

This in itself doesn't change the attackers position significantly:


Exhaustively searching for the correct key becomes more complicated because now the given 30 bits of the MAC might match but it might still be the wrong key. However there are $2^{128}$ possible keys and by the birthday paradox a MAC collision will probably occur after about $2^{64}$ message block. So this is the more plausible target anyway.
When a collision occurs the attacker can now not readily detect it anymore because only parts of the MAC are visible to him. On the other hand it will potentially be easy to submit fake queries to validate potential collisions and the probability for a collision doesn't change when the attackers view is truncated.


So in this case it would be fine to keep the values but I would love to hear how this makes sense.