Calvin Tower knowing Roland's language?

Question:

In Song of Susannah - how does Calvin Tower know so much about Roland and more importantly, how does he know the Roland's language?

If Charlie The Choo Choo can show up so blatantly in lit,

Spoiler

what makes you think that Roland's potentially infinite loop hasn't been chronicled in something else that Tower has read and he just picked it up from that. Haven't read it in ages, but DTVII makes it clear that this is likely not Rolands first time at the fair.

Ka is a wheel.

I am on my second reread of the series and I passed this off the first time, but since i read this last night its been bugging me Who the Hell is Cal Tower.. What I finally came up with was that at one point Eddie makes the comment that the vacant lot was Never Cal's he was just the guardian.. and we know that the Manni have been known as great travellers, so whats to say that at somepoint another gunslinger (Steven Deschain or perhaps his grand-pere Aleric of the red hair did not pay one of towers relitives and appoint him and his desendants as guardians, much in the same manner that a gunslinger recieves his father's guns as his? Just a thought

Not just him -- his ancestors. His great-great-great grandfather, Stefan Toren, was also a guardian of the rose.

My fault I didn't capitalize Tower's meaning Toren, it was still early when I posted