"and this together with lack of possibility(?) to verify total loads applied to a face"
calculate the total force of your nonuniform pressure, make a simple part, apply your non uniform pressure, measure reaction force, compare forces to validate. we call this a "smoke test" in our one-on-one mentoring. good habit regardless of what you're doing.
what i find easiest for developing the equation is to start in excel, once you have the coefficients of the equation, its just a matter of plugging them in.
something that might help is start with something that has examples like rho G h for hydrostatic pressure. then you can expand from there.
what would you want to see for a better input method? you can always submit an enhancement request through the customerportal.
I agree on Your "smoke test" approach. However, it would have been a NICE feature to click a face/vertex/whatever PRIOR to running the solver in my "real" model, to get listed the sum of loads applied to the selected item.
Your proposed Excel approach for the equation is also agreed upon, and for the most is a more-or-less straightforward task. However, in my business (and I suppose most other fields) 95-99% of non-uniform loads are LINEAR, where you know min/max values, and/or rate of growth. I therefore think SW should include an option for application of linear variable loads (in addition to the existing equation option, of course) Such application of linear variable loads are common in i.a. all beam-analysis software I have used for the last 25 years, and should be possible to include in SW as well.
My original point was that load application to any model should be the "easiest" task during the simulation process - but the way SW have laid out the non-uniform loading regime, it have become the most time consuming after part modeling and contact sets.
But, again You are right. I should submit ER instead of complaining here...
A library of loads would be a good one. Have you tried saving one you setup as a library load?
But I agree, your enhancements would be good ones. I think you will find you just have to vote on existing ones.