One thing I dislike with this is that, for insert until level 10 spells is well, but then we have a barrier, and directly in level 50 we can insert any level spell, creating runes or items with embeded spells in a too big step.
How about the possibility to embed 11+ level spells between?. If with lvl 20 we can embed lvl 10 spells in runes and items, we should be able to embed lvl 11, 15, 18 or 20 (some examples) within levels 21-40.
I am talking about Rune Mastery and alchemy spell lists.
Seek for a lvl 50 alchemist because we want a lvl 15 rune is a bit exagerated IMO.
A solution could be to use "virtual" spells within 21-50 range, in the way than other ones, so for Rune Mastery, if we have 28 ranks, we can write until lvl 14 runes.
For alchemy the same.
Using spell research is not much appropiate and not realistic for game because no one can spend so much time researching so many spells (the lvl 22, 24, 26, 28, 32, 34, 36...etc etc), so they should be virtual or be included in the list, it is not typcical, but items are really a special case.
Note: for alchemy if needed for our game system, because using the limits we only can embed greater than lvl 10 in 1 use items, I would allow it for potions too (as they are 1 use items too), and for creating the rune paper there is no need as the current lists have for create lvl 20, 30 and 50 rune papers.