Below is known problems with importing of 6.1 uml projects in 6.5 and later releases
Can't open deployment, component, collaboration diagram
It's a known issue (see issue 142163), these diagrams was missed from new uml implementation but may be implemented later. Community efforts are welcomed here.
It's a know issue (see issue 156792), 6.1 uml module have an issue in this area and save diagram in system encoding but specify UTF-8 in xml header. After implementation of a part fix you need to open you diagram files (etlp and etld) in any editor and replace UTF-8 with correct encoding, save changes (do not save in another encoding, most editors will no alter encoding on Save action but may change occasionally with Save As). For example windows Russian encoding should be "windows-1251", do not mix with "cp1251".