We have noticed this issue as well after a fresh install of Eclipse and the WPIlib plugins.
Have your teammate create a new Robot Project using the plugins. When they create a new project for the first time, they should be prompted to enter the team ID. This entering of the team ID seems to be a critical step in the completion of the installation.
Once, the team ID is entered, my guess is that the errors in your imported project will go away.
Our general rule of thumb for setting up a new developer machine:
- Install Eclipse
- Install Plugins
- Create one Robot Project (and then optionally delete it)
- Then import other Robot Projects from shared files or github
Hope that helps.