Well, some more ideas. The glyphs in game, as I understand them, would be small stones with symbols on them. The symbols would represent words of power infused into them by... I guess Talad if I'm reading everything right. Color doesn't really mean anything other than a means of identifying the category of words the symbol on them represents. Those symbols would require interpretation, and meaning, and if they were to somehow represent a gods language, one symbol could have many meanings and usages with varying powers in each one. You would have to be taught the meaning of the glyphs, how to pronounce the words correctly, etc...
Then, add to it that a person's ability to manipulate their own thoughts is a learned skill. Meditation can be a tougher skill to learn than sword fighting. All the emotional baggage that people carry can corrupt the purity of their thoughts and make even the simplest directed thought impossible. Add that in, and all these teachers around the area are really spiritual advisers as much as anything else. To channel the energy of the glyphs, you have to pull it all together, pure thoughts to channel, speak the words correctly, perhaps even hold them correctly. So I still see value in the trainers around the world and the system in place.
Now, this is all my interpretation. I could role play it like this, but it doesn't mean it's what the games authors (i.e., the lolgods), intended. Till it becomes lore, it's hard to say how to roleplay it right. I do not understand the purification process described and how that fits in, unless you consider purifying them to be part of the understanding of the symbol. After that though, the combining of them would be based on the players knowledge of the words/symbols on them and how to form more powerful sentences with them. That seems within terms of what could be expected of the glyph magic system in game and in character. I think the process of researching could be a bit more involved, but no biggie.
As for other players telling each other the recipes, well, perhaps there should be more consequences, like backfires, to keep powerful mages from sharing too powerful spells with young acolytes. Otherwise, you can't really stop that, and I would put forward other players, if you really want PS to be about role playing, should be able to train up other characters if their skill is higher. They can charge what they want, and the trainers in the world are just a sort of check on making sure people don't abuse the player base.
What bothers me the most though... why are they all standing around on street corners all day long? Shouldn't they be off in a cave or a study somewhere focusing their thoughts?