Are this quest possible?

[Titka]

[That which creates can also destroy]
I throw the seed on him and he dosen't come down. I tried to reach him, but I'm nowhere near reaching him. There was some other quests that I couldn't do because mobs didn't come down.

[Czarnowron]

So, yeah, the problem you described actually exists.

Normaly you are supposed to throw the Seed of Nature's Wrath at one of the Reanimated Frostwyrms which are flying at the north of the Wyrmest Temple -- and then the wyrm should fly down to you, so you can kill it. Yet, it doesn't do so. How I dealt with this bug (?) is that I first weakened it via the Seed and then tried to pull it with a range spell (it was Exorcism I used, so 30 yd range, not much). I followed the wyrm for like 10 min and then, when he got close to some hills near the Coldwind Heights, I climbed them and successfully hit it. Then it came to me and we fought, I slayed it, gg, objective completed.

So yeah, I guess that is the only way to do it nr. Either follow it and try to shoot it with something or (if you don't have any large-range abllities, team up with someone that has it). You can also wait untill you learn Cold Weather Flying and then simply try to fly into the wyrm's aggro zone.

In Emerald Dragonshrine, there is a quest (The Plume of Alystros) with a problem of the same manner -- you are supposed to use Skytalon Molts to pull Alystros down from his piece of rock he is sitting on, yet he will never fly to you unless you can pull him directly with a range skill or attack.