Hi Michael,
Thanks so much for reaching out!
You are correct, unfortunately there is no form validation other than marking a field as Required.
If you’d like to try your hand at this customization, I’d recommend starting off by taking a look at our Themer’s Guide, which can show you which templates can be edited and copied in order to achieve the results that you are looking for.
You can also add this idea to our Feature Requests, as we tend to implement ideas based on customer feedback, so your input is greatly appreciated:
https://tribe.uservoice.com/forums/195723-feature-ideas
Let me know if you have any other questions on this topic!
Thanks,
Jaime