I agree with the OP:
addgraphic(string, string) works, while addscaledgraphic(string,string) throws a an error like this:
/tmp/plugin/FGAAAAJgXh4J/pkg:/source/regScreen.brs(320): runtime error f4: Member function not found in BrightScript Component or interface.
Documentation looks to be wrong in both 2.6 and 2.7 versions. The former method with 2 parameters is not listed in the doc, while the latter method does not work.