First of all thank u for all your work and passion. Thre HRE faction is needing some love in my opinion too.
Relic said that they dont want to nerf mongols by design so they have to step up other civs like HRE with more uniqness.
BUT I played now over 600 games with HRE and will comment to some points of ur posting were I dont agree on so pls dont be mad abaout it. Im apreciating it rly.
A new or usefull unique units is the right way to go but i dont thing that a cav unit is the right choice in AoE4. Because they are namened and desgined as a infatery civ so I thing it would be better to put the dev time into the landsknecht or a gunpowerder unit.
Im totaly against this!!!
Yes the regnitz is realy strong atm but i cant balance it with more slots out because u would undermine the aspect of HRE that u can store reliqs over ur 3 needed for regnitz into keeps and towers. This would cut the HRE uniqness even shorter and this isnt they way we want to go.
I realy like that idear
this is a good idea too. I suggestioned it in the HRE rant post last year too
again i agree and it was suggested last year.
A good choice if the LK isnt getting a rework with weapon switching.
I thing they should have a compareable movementspeed than spearman. If they would be faster they would screw up formations and they should drive in formation with spearman so a Statbuff would be the right choice.
Over all u did a good summary what is written in the HRE uniqness threat HRE - Uniqueness, mechanic and army rant. There is a lot of potential lying fallow - #318 by Jaysus04 .
Added woth additional good ideas 
Probs 