Can you post the text of your email? I’m curious what it says.
I doubt that there will be any difference before and after CE/FCC certification in the modem, but maybe the testing for FCC certification will find something that requires more shielding. The chips (RS9116, BM818 and PLS8) already have FCC certification and CE certification is basically a rubber stamp since it is self-certified.
Purism says that it will provide firmware updates if any, so I don’t think you are running much of a risk by ordering now.
I would call/write Purism and ask if they can send the phone, battery and microSD card in the same box to save on shipping costs.
You can check whether the places where you want to travel have support for the bands on the BM818-A1 to decide whether it is worth buying.