Hi mac721,
When you update a plugin, the language folder is overwritten. So better practice, before updating a plugin you can take a backup of the PO and MO files. Once the plugin update is done, you can upload the backup. So far all the string is translatable in fluent support free and pro except for a few button text and status values and some other. Also, the string which is customizable by the user is not available for translation. For example, “Create a New Ticket” is not translatable for the pro version. If you use the pro version, you are able to change the string from the ticket configuration form, from where you are able to change the sentence or translate the string and save it to the database.
If you still need more clarifications or assistance, please submit a ticket. Our dedicated support team will help with this.