[Snowball]

64 is pretty low for level 40. The cap for that level is 114. You probably want at least 100ish to land Sleep reliably. If unresisted, Sleep lasts for one minute.

The yhoat scroll is about 150k, and altep is ~50k. It sounds like a lot of money, but compared to the trouble you're going through it's really not that much and the rewards are more consistent. At the rate you're going you might spend 6 hours attempting those quests, lose some exp in the process and if you're unlucky still end up with nothing. If you spend that much time farming say, giant spiders in altepa, you're much safer and would probably collect nearly enough spider webs to pay for both scrolls. It's more boring, but also safer and more consistent.
But, y'know, do whatever is fun for you.

Killed about 2-3 giant spiders today on the way to Alteppa (with WHM/BLM) and what did I get.... absolutely NOTHING at all! (well apart from a few exp, but that was about all I got. /sigh!)
What a complete waste THAT was! I might try killing them with WHM/THF next time.

I'll have to go back and check it out again, but if that scroll for Tele Alteppa is around 50k on AH, I might just have enough, by the skin of my teeth, and perhaps buy it instead. Ill have to think about it.

As for the Tele Yhoatar quest one..... I'm going to wait now til I've gained maybe 2 or 4 more levels of WHM, then I'll feel confident enough to give it another shot without the worry of aggro from the goblins getting in the way!
I'm definitely NOT paying 150k for a scroll I can perhaps get with a few tries a bit later on!
WAAAYYYYY too expensive in my opinion Im afraid!