But that makes any list of all formula quite inconsistent.

I'm also not so sure that other games really have this... at least not in the usual game content... the usually have a list of abilities or skills you will learn with higher levels (and if you invest the right amount of "points" in the right places). That would be missing in istaria and maybe it would be a nice thing to add that...
But they usually do not have a complete list of formulas and formulas need to be looted in those other games, that I know of that have something comparable, in the same way as here... also spells, if there is something like spells and not just a handfull of "magical" abilities, are not included in some list that just keeps track of what you have and what you don't have. What I know are lists of what I have...

And, that is where you have to give credit to the devs, the system in Istaria is quite logically today... you have the tier system, usually with "half"-Tier steps, i.e. every 10 level you have an updated form of something you already know. Then the forms themselves are not that surprising either (all types of weapon, all types of armor, scales, ...).

The same goes for spells. If you learned a Lightning Bolt I at level 1, you can get the Improved Lightning Bold I at lvl 10 and then get an updated version of the spells every 20 lvl.
There are only few things that don't fit into this system. Even the new confectioner forms follow that system. And the old confectioner forms on the other hand are a very good example of why you do not want a list of all possible formula in the knowledge window...

If you really think it is necessary, Amon explained how to create some encyclopaedia style stuff, where you can look up things in game in another window (if I understood that correctly)... Maybe, if people do it right, they could integrate it into the client at one time... but don't put all that unnecessary stuff into the knowledge window. Even now, with only the stuff that my char knows in it, I am painfully missing a whole lot of filter options.