Hi Robert!
Thanks for reaching out to us! 🙂
Unfortunately, that is not something achievable by theming the template. The event description field is actually the default WordPress post content. So, you would have to try making a customization of some sort.
Just to set expectations right, let me tell you that we can’t give support for customizations as it’s stated in our terms and conditions. That said, we really do like helping out and pointing the users into the right direction.
There isn’t an easy way to add “maxlength= #TBD” to that textarea, you could do so by modifying the plugin core files (which we don’t recommend because those changes would be lost when updating the plugin). The other option would be to write a JavaScript snippet to do that, which is not an ideal solution.
I’m sorry I can’t be of much help here. Do let me know if you have any questions and I’ll be happy to help.
Best!
Victor