In general, please don't post in the feedback forum - it is for feedback specifically on the site. :-) I have been moving your posts to the general forum - here's a link: https://www.infopathdev.com/forums/41.aspx
I usually add a field to my form for the form name - you don't have to show it on the form, you can just add it to the data source. Then, in my submit rules, if that field is blank, I set the field to the name I want to use, and I set up my data connection to use that field instead of using a formula in the submit data connection. So - create a field for the name, change your submit data connection to use the name. Change your submit to use rules, and have the first rule check to see if the field is blank. If it is, set the field to the formula you want to use for the form name. Then add a rule to submit the form (and one to close the form if that's the desired behavior). Now the form name is stable, and stored in the form's main data source. Hope that makes sense. :)