Hello,
I saw about built-in feature, but that is only for single text, not number field.
About translations, unfortunately link didn’t help as those verification messages isn’t in backend under validations nor loco translate can find string.
Also, with another custom verification there is string Form has not been submitted, please see the errors below which also isn’t in validation messages or in strings inside plugin.
Can you point me where to look for those messages? Is that something from WordPress which have 100% translation in Loco translate or somewhere else?