The FromChars property in the GlobalConfig contains the list of characters that should be converted before checking a word. See also ToChars.
Remember to recycle the application pool after reloading the modified GlobalConfig.
<SpellConfig
...
FromChars=""
...
The length of the strings FromChars and ToChars must be the same. Characters found in the first string are replaced with the corresponding ones in the second string.
The default value for FromChars is the typographical apostrophe (ANSI 146), with the ASCII apostrophe of code 39 as the replacement in ToChars.
The default value corresponds to the standard apostrophe, inserted by the system script EditInsertCurlySingleQM.
IMPORTANT: To make these changes available to the GN4 users, after you saved the GLOBALCONFIG.XML file and imported it into the database, or after you modified it in EdAdmin4 and saved, recycle the GN4 application pools on all IIS servers and then make all users log out and log back in.