No, Emvi does not support private tags. But usually you won't need many tags to identify it for everyone. I was looking for the fixed IP addresses of our local network recently and couldn't find them by searching for "IP", because it was tagged as "network". Adding IP as a new tag is beneficial for everyone.
You can bookmark, watch, or create a (private) list for stuff you look up frequently.
For my work notes I've been copying links to the team docs into my personal note taking system and organizing those as I wished