that sounds super complicated and not something I’d even want to think about attempting to do.
The point overall is to make it more open, which fits the overall theme of Open Legend, which partially is about finding an Attribute to do the task you want to do, and having an explainable reason for it to work. That is part of the reason when a player says they want to do something I say “sounds like _____, but if you have another attribute in mind and can convenience me of it, I’ll let you use that”
There can be situations where some Attributes won’t work for initiative given special circumstances, but allowing players to use their best stat is part of being Legends too.
You could certainly try taking some sort of average of all of them, but, again, that sounds complicated and I’m not sure it really makes too much sense to do. A person that responds really fast with their muscles doesn’t often worry about taking the time to logically look over the scene. A person that can summon magic with their mind doesn’t need fast muscles to suddenly shoot their magic out, etc.
If in a particular campaign you wanted to emphasize diversifying points, I suppose you could.