New Zealand customs didn't ask me anything like that.
The customs officer was "difficult" though, even though Fedex were acting as the customs agents. While not all customs officers are difficult, I expect the difficult ones are universal. Maybe you just got one of them?
There are Material Safety Datasheets for the ink and the solder paste at https://support.voltera.io/hc/en-us/articles/115004414348-MSDS.