I think most paths near Engelberg are signed according to sac standards so T1 yellow T2 and T3 red and T4 and more difficult blue. I did not see many old and or wrongly signed paths in this region. But I only know a few near Engelberg. A white-blue-white T1 does/should not existing. That part of your message is not completely clear to me. 

The 2023 SAC revision makes the boundary’s between the grades less strict but this did not change anything outside. 

If this path has blue marking you can tag it T4. If you think it is a T4 you can also tag it as an T4. If you want to leave the note open or want to close it with or without solving the issue than that’s also fine by me. Happy hiking and mapping.
