The title and description of finder groups are protected using UI escape sequences similar to colors (|c|r), links (|H|h|h), textures (|T|t), and so on. Custom code cannot read it and there's no API available to translate it.
https://wowpedia.fandom.com/wiki/UI_...tected_strings
What your code is really seeing in your example is the string
|Kr445|k and when it's printed or otherwise displayed by your code the UI formats it into the title you see which is +15. The number 445 is the 445th group your client has loaded to show you since the last time the client started; the number will continue to increase persistent across logouts and reloads until you exit the game. If you saved any chat messages mentioning the group name, such as a chat history addon, those group names will load as "Unknown" when you start the game since there is no longer a group with that ID in the C memory.