Been trying to get the ten friend achievement and I can't (despite having added 10 people). Not sure what the issue is, but it might be that everyone I'm adding has a fat friendlist. Add me and comment so I can add back!
You most likely already have the achievement if you've added 10+ friends, it'll just take awhile for it to show up cause it's buggy af.
Few other places you can check;
"Profile" Scroll down and look at "Recent Achievements" - this one tends to not work properly, takes a few days
"Profile > Achievements" look for the "Party Alien" card that is unlocked
"Profile > Artifact Presentation Room" look under the Power section for the card that says "Magma Transmitter Hull (Bronze)" it looks exactly like the same card as the achievement one.