It's be nice , at the moment that you are designing/configuring a formula, to have a kind of formula checker so as to verify formula sintax.
Thanks for your suggestion Fernando.
We have incorporated this feedback into our latest formula builder in Universal Forms.
I will update this feature when we get closer to release of Universal Forms for SharePoint.
100% agree - this is basic functionality which is missing from Nintex - You would expect this is done when you pay so much for the product!
Steve Dark commented
Being able to validate your formulas at design time (like InfoPath offered) would be a very desirable feature to add.