Before executing an AppleScript script, its source code must be compiled to a binary form. This requires the presence of all of the script's target applications because the compiler needs the application-specific dictionaries. Sometimes accessing an application's AppleScript dictionary requires launching the application (as is the case for QuarkXPress, for example).
Starting with Switch 08, SwitchScripter stores the compiled binary form of the AppleScript in the Switch script package (in addition to the source code) to avoid recompilation at execution time. This has several advantages:
It is possible to execute portions of the script that do not need the target application (such as perhaps a property validation entry point) without launching the application.
The name of a target application can be determined at run-time by the script (as long as the dictionaries for the alternative applications are compatible).
There is a small performance gain because the compilation process is skipped.
When you edit AppleScript source code on Windows, SwitchScripter is unable to generate the compiled binary form, so any compiled binary already present in the script package is removed (to avoid inconsistencies). However, as long as you do not change the AppleScript source code the corresponding compiled binary remains untouched - also on Windows.
In summary, you can safely edit a multi-platform script package on Windows as long as you do not touch the AppleScript source code (or in case you do not mind omitting the compiled binary).