I have a mixed Scala/Java project on GitHub. Java classes that reference Scala libraries (such as Akka) have erroneous error messages reported in the editor, but not in the Problems tab. The GitHub project is here: https://github.com/mslinn/akkaDoodles. I have taken a screen shot of a working program that compiles with no errors, yet the Java editor shows errors. Other Java classes look even worse.

I used sbt and sbt eclipse to create the project.

IntelliJ IDEA is also confused, BTW.