Yes, except I think there is an exception if a file is opened in the jsl editor from a gb2312 encoded file. Saving that editor window back to the *same* file might use the original file's charset.
I think savetextfile() also has a charset parameter, you might search the scripting index ... I think there might be another function that uses an explicit charset.
edit: Only loadTextFile() and open() have the charset option, for reading. Wish list here: charset for saveTextFile
Craige