Um, I think you're going to need to be a little more specific! Are there specific combinations or research items you think are poorly priced?

I can't seem to get my words properly together but it basically is:
Why are the creature's production cost so high for coal?
Why is assassinate is so powerful?

That's a deeper question than it may appear. Coal cost in IC (all the way back from vanilla, not just in Tel) is determined essentially by how "powerful" a creature is. Its stats are put together in an equation that determines the creature's coal cost. The equation that governs this is tuned based on community feedback from online matches. We've been doing this for a long time and all of our balance decisions are based on online play trends and player input. There is no simple answer to "why does everything cost so much coal" because it's all part of a wider picture with many facets. Costs in Tellurian may seem unusual to you if you're new to the mod or just returning to the game, but it's important to remember that Tellurian is a distinct entity from the base game and Insect Invasion and as such has a different gameplay style, different meta, different units, et cetera.

As for electricity, it's based on what abilities a creature has, just like it has always been. There is some additional scaling in Tellurian, however. For example, creatures with Pack Hunter will cost more electricity based on how much damage they deal, since Pack Hunter modifies attack. But essentially electricity behaves the way it always has.

Assassinate is a difficult ability to tune, as the only parameters we're capable of editing are how much damage it does and how much endurance it uses. There's a fine line between the ability being OP and the ability being not worth using. I think we're about as close to that line as we're going to get at the moment, but we always value input.

I don't mean this to demean you, but it seems based on the points you've brought up that you don't play very much multiplayer. Tellurian is developed first and foremost to create a fun and balanced multiplayer experience for the more competitive side of the community. If you're used to playing against the AI or in private matches with your friends, a lot of the changes we make may not make much sense to you.

With that being said, you are more than welcome to join us over on our Discord server[discord.io], either to play or to engage in further discussion. There are other team members there more well-versed in the balance side of the mod who can probably give you more detailed answers than I can. :)