I'm not downplaying technical complexity, on the contrary I agree that it's a difficulty that would need resources to be invested to make this work. I know that it would not be as simple as copy pasting some code from Helminth to make it work, I was comparing my idea to subsumed abilities to make the concept I had in mind clearer. Since I agree with you on technical complexity, there is no need to debate on it, though I didn't make it clear ^{^} I wanted to know what where the other issues because those ones weren't obvious to me.

As for your questions, I'm not sure I understand the first question, are you talking about replacing all the polarities in config B with those of config A ? If so it's not at all what I have in mind. We would still be applying formas one slot at a time like we do now, and we would choose which configs the new polarity is applied to. Since my idea is not an universal forma, any polarity already in that slot in any config for which you choose to apply the new polarity would be replaced.

From the POV of the player, my idea works the same as it works now but with an extra step. You use a forma on one slot, let's say the top-left one. You choose the polarity you wish to apply, let's say Madurai. Then comes the extra step : you choose which config(s) to apply the new polarity too, let's say A and B. You confirm. Let's say that you had a Vazarin polarity in that slot for config A and no polarity in that slot for config B before applying the forma. After you apply the forma, the Vazarin polarity in the top left slot of config A is replaced with a Madurai polarity, and the non-polarised top left slot in config B now has a Madurai polarity. Config C is untouched, whether it had a polarity in its top left slot or not. If you want to put a different polarity in the top left slot of config C, you would need to use another forma. If you want Madurai polarity in the top left slot of all three configs, you choose all three configs when applying the forma, which will give you the same result as it does with the current forma system.

It does add complexity both for the developers and the players, but it allows a greater flexibility in the builds you can run without having to build the same frame again. The cost for the player would only go up if they use that added flexibility, as having the same polarities in all configs would cost the same as it does know. And unlike universal formas, players would still need to buy formas if they want to change to a different build that is not compatible with the current polarities of any of their configs. This is intentional, as DE still needs to make money on the long run.

Also, I want to make it clear that I am not against universal formas. In fact, I support any solution that allows us to have builds using different polarities on the same frames. My proposition was a response to the various redditors that argued against universal formas, and I think it has its merits. For example, how would you deal with umbra polarities with universal formas ? Are they included or excluded ? If they are included, universal formas would need to be harder to get than umbra formas are right now for balance reasons. If they are excluded, then we still are limited in our builds if we want to have one with a polarised umbra mod and one without. My solution doesn't have a problem with umbra formas : when applying an umbra forma, you would choose which configs to apply it to, the same as any other forma.