Hi @poancia,
I’m sorry to hear you’ve encountered a fatal error 🙁
The error message itself though indicates that the problem lies within WooCommerce Multilingual, which is not our plugin. My guess is they have code that can interact with Event Tickets (our RSVP plugin) and they are assuming you have that installed – but, based on your system information, you are not using.
What I’d recommend is talking to the authors of that plugin and/or temporarily deactivating it until you can arrive at a solution.
Does that help?