Would it be possible to write an addon that allows you to out a Char in a blacklist wich is no longer able to read motifs, recipes and other items like that.
Perfekt would be if you would be able make a personal list with the motifs and recipes that you can no longer read with chars on the blacklist.
It seems like that would require hooking into UseItem. Maybe someone has a good way of doing this, but if you even look at UseItem's distant relative now, it'll throw an error and you have to reload.
You could try to use FCOItemSaver and set it up to use character settings, instead of account wide.
Let it mark your unknown recipes and motifs (no unknown check here, it'll just mark all) and remove those markers that you don't need anymore for each character.
It'll prevent the usage of the marked items in your inventory.
But it got several other features you possibly don't need so you need to check it out.