Hi there Bryan,
Thanks for getting in touch with us! I can help you on this 🙂
Seems like the ‘One ticket’ string is part of the theme you are using and not actually part of our plugins translation. From what I see in the system info you are using a custom developed theme, right? Try searching for the following string inside the theme folder (many code editors have the option to search in a folder): ‘tribe-events-event-cost-descr’. That string is the class of the element containing the string, once you identified it you can translate it with a snippet or with the Say What? plugin.
Please let me know if that helps,
Best,
Nico