>>Add a string element with value <language ISO Code> in Info.plist to the Spelling Service and UserDictionaryService Element or HyphenationService element. Depending on the operating system and InDesign version, you can find the file Info.plist at the locations listed below.<<
I cannot update the property list "Info.plist" when I use the TextEdit app. It says that I do not have permission. I did a Get Info on the file and tried to give Wheel and/or Everyone write access, but it would not work.
The plist is located at /Applications/Adobe InDesign CC/Resources/Dictionaries/LILO/Linguistics/Providers/Plugins2/AdobeHunspellPlugin.bundle/Contents/
Note that the Plugin.bundle is a package and so I had to "Show contents" to view what it containted.
Sorry to hear about the trouble you are facing. I would suggest you provide read & write permission to "AdobeHunspellPlugin.bundle" once you do that, you should be able to modify the "Info.plist" file. If you are still unable to do so, then you may right-click on the file, click copy and paste it in Desktop. Edit the file and copy & paste under the original location. Now, you will be prompted to provide your Mac user login password. Once you enter the correct credential, the edited file will replace the original one. I hope it helps!