For custom package BCM43341 , Do you mean you get a customized firmware from other support channel? not using the released firmware in SDK . I just check 43340 in 6.2.1 , it has no CLM divided, so this should be no problem . I think you need to upgrade nv+ firmware together from 3.5.2 to 6.2.1 if you still want to use the old one.
Since this appears to be a custom implementation of our firmware, please disclose your chip supplier so I can talk to them about the engagement model that was agreed upon. Note that our support team on the community is trained to support standard broad market implementations of our firmware. For custom implementations, the chip supplier themselves should lean on us directly for support through the channels we have setup for their use.