Symptom:
Script Editor is removing # from Custom Functions formulas during Export/Import.  Script Editor should allow you to fully export and import Custom Functions it allows you to define and save.  If special characters are used for substitution the syntax must be well defined and documented and there should be a vehicle for including (e.g. escape) those chars.

Conditions:
When exporting or importing custom functions.  Unsupported characters list is missing in ICM Script Editor custom function configuration guideline.