The validation messages when filling out a form are unusual/non-standard for forms, such as the email field. I would consider this a bug.

Example: Email field. If you enter an invalid email, the validation message says "Guest email is invalid" but this is an unusual message for this. It should be something akin to "Please enter a valid email address." A message like "Please enter a valid email address" applies to both leaving the required field empty AND the email being invalid.

The best solution to this overall would just be to allow us to set the validation error message ourselves. In general we should be able to set custom validation messages on each field, so this is also an enhancement.

Example 2: Checkboxes.

If I have a checkbox field that requires at least one to be checked, the validation message is not very good. Let's say I have a checkbox field called "Subscribe to" and the two boxes are "Newsletter" and "Podcast." If neither are selected, the message will be "Subscribe to is required." This is technically correct, the field is called "Subscribe to," but it would be much better if a custom validation message could be set to say "Please select at least one option."

I have seen this ability in other form builders, such as Forminator, where a custom validation message can be set.

At the very least, it should be easier to change this. Currently, it requires a fair amount of custom code in an html element that uses css and javascript. Due to the html element not allowing anonymous functions anymore it is quite a bit of lines of code to cover all the bases.