Hi,

in my case, I have GND via under the holder.
It is the same GND as the battery, so no risk for a short/issue.
do you think it's ok?
there are any certification requirements?

 

Welcome to AAC!

Don't see a problem. Regarding certification, it depends on the certification requirements. It would only be a problem if they require no vias under components.

 

Apply the glued on insulator-tape between via and battery. Or apply the battery holder (plastic envelope)