I understood your purpose, and to finalise the patch,
If we go with the 3rd p...

I understood your purpose, and to finalise the patch,
If we go with the 3rd point, Can we simply use the
dependency on "transliteration" for the "Webform file rename" feature, and
use the function - (transliteration_clean_filename) to clean the name with
translation ?

Like we have a checkbox "Rename file name after upload" If user check this
checkbox. we validate module_exists for "transliteration" and it gives an
error message of dependency. if you want to use this feature you need to
download "transliteration" module.?

Otherwise, if we choose to go with step 1 and 2 then we need to do
modification in "webform_file_rename_clean_name" function.

What will be your preferable way ? Waiting for your suggestion on this. :)