Unsure on whether or not Atiesh should have a gem or Ashbringer should not, but probably something that should be consistent across both. As a lot of you have pointed out, there are a number of card general inconsistencies that should be addressed even if all of them aren't as clear as this one. We fix a number of them with each update, but new ones tend to crop up as a result of new cards. Functionality of a card in code can usually be turned around quickly because the contents of the change live on the server and do not require an update. Unfortunately for text, the information usually lives in the client. As a result, it has to wait for a client update to be changed. We try minimize the amount of client updates we do so we aren't frequently requiring new downloads. In any case, this stuff is still clearly worth fixing, I think it's just generally interesting to understand the process. Sometimes cards can appear to be inconsistent when really we made a judgment call because even though a text was slightly inconsistent, it made that particular card much easier to understand on the first read. That's why it's great to get feedback from the community on this stuff so we can learn whether or not our judgments were poorly received or went unnoticed. Other times, bugs just slip through the cracks. This will always happen (with every game ever), the hope is we learn more with every release so they become less prevalent.
On the topic of tokens, I wonder what the general consistency would be. On the one hand I think a good blanket rule might be that all non-collectible cards not have a rarity gem. On the other hand, if we ever made a card that said 'destroy a rare card', I wonder if it would be jarring to find out that you could not target a Feral Spirit minion summoned by Feral Spirits because the token is not actually 'rare'. Curious as to what you all think. Thanks for bringing it up!
Molten Giant was part of the nerfs to prepare for Standard. Certain archetypes would just be evergreen if we didn't hit them, and the meta would be the same each year. If Molten Giant had been in an expansion it probably would have been fine to let rotate into Wild. It's an argument perhaps for rotating a couple cards from Classic instead of nerfing them if Standard is at risk of being stale because of the evergreen sets in future rotations.
We have a huge team of people, but the team primarily responsible for balance does have folks with many years of experience balancing card games.
We've definitely made balancing mistakes in the past, and have had to nerf cards to fix them. We'd prefer to let the meta shift through a combination of new cards and players discovering new decks, but we carefully monitor the power level and prevalence of decks and have nerfed when things have gotten really out of whack.