@Elias thanks for looking into this I understand the implications so if the suggestion from @mburk is easy to implement this would be already a very helpful first step to speed things up, however I still feel my suggestions would improve the experience with spread pins but understand it is not that trivial but would really like you to consider this with a major version
regarding your other points ether skip d) or you just treat every pin as a potential single value or spread input pin so you can connect both in any order you want would off course be even more flexible in case of fuse you could often than just group things by cons and than put it all together in the final node, seems to make things more elegant the more I think about it
f) maybe it does not need to offer a new pin but when you drag a link on to the pingroup area this gets high lighted so you are aware you do pin group interaction once you release the mousebutton when the system reorders inputs and creates pins, same for reordering