Evan Martinez just posted the following in an unrelated thread... could be your answer? I'll quote him:
"we did have another feature come out that could be helpful in this instance, custom data rules. Custom data rules let you use the Quick Base formula language to put rules in place on when a record shouldn't be saved, you can even put in your own error messages when this happens and they work across any type of data entry including grid edit, import, and APIs not just form rules...
I hope this is helpful and I have linked two help topics on custom data rules below.
https://help.quickbase.com/user-assistance/1/validation.htmlhttps://help.quickbase.com/user-assistance/formulas_custom_data_rules.html?Highlight=custom%20data"
