Word of warning, this is mostly negative feedback. Don't let that discourage you though! I always like seeing what kind of fan cards other players come up with, even if I end up critical of them. Thank-you for sharing yours.
First, an overall thought to consider. You say that you are working on a fan expansion. If you intend for it to be an actual expansion rather than just a collection of fan cards, then you should try to come up with a core concept or theme around which you can build the set. Official expansion-specific concepts should be kept to a minimum if they are used at all. I wouldn't touch the prizes (which are very much a Cornucopia-only thing) and I would be wary of adding new Durations. I would shy away from anything involving coin tokens or victory tokens because those are specific to Guilds and Prosperity.
Tavern -- This is far too powerful. Prizes can't be handed out so easily. This is swingier than Tournament, which is already among the swingiest.
Eldermen -- should cost more, but otherwise not so interesting. That's not necessarily a bad thing, but yeah.
Town Council -- The wording doesn't work well. "Each Treasure in your hand" does not allow for accountability. What if I draw more Treasure cards after playing Town Council? It should be rephrased as "Each Treasure you play this turn". This still allows for potential confusion with Counterfeit if casual players aren't careful. Perhaps the bigger issue is that the concept already exists in the form of Bank, which has a more elegant wording. Maybe an action version of Bank would be OK, but it does lower interest (pun not intended
).
Chainmail -- This kind of discard attack is already extremely powerful. It's almost as strong as Pillage, which is so powerful that it had to be made into a one-shot. The discard on this is unbounded which means it has the potential to pin a player. And then it Curses on top of that? That's just too much for one attack. As for the reaction, you need to add a clause to prevent it from drawing your deck. In Dominion, reactions can be revealed as many times as you want. This is why reactions are either idempotent or they are discarded or set aside when used. But if you do that with Chainmail, the reaction is basically the same as Horse Traders' reaction.
On wording, if the discard is mandatory (you say "must") then you need a hand-revealing clause for accountability (see: Cutpurse). You can omit the "must". If the text doesn't make it clear that the action is optional, then it is mandatory by default. And the Curse part should be, "If he does not, he gains a Curse." If a player cannot do something, he does not do it. Saying both is redundant.
Looking at it from a design perspective, perhaps the reaction was intended to be a counter to its own attack. Even so, that doesn't justify the strength of the attack. Reactions aren't 100% reliable and you don't want to force players into buying a specific card every time it shows up. One final thing to consider is that people tend not to like attacks that hurt others without giving any benefit of their own (e.g. Saboteur) even if they are strong (e.g. Sea Hag). You can do it, of course, but it's something to think about.
(PPE: @Qvist, your or-clause isn't the same. In the original, you don't get a choice.)
Wiseman -- Too powerful for $4. Needs to be at least $5, I think. The first possibility really pushes a BM strategy. The second possibility is rarely more than a consolation prize. Very odd, but might be interesting.
Relic -- Probably works, but it's just not that interesting. It could probably be $6, maybe even $5 since it's terminal.
Homeless Shelter -- Could work. Not sure about it though. It's a village, which means that it will either be terrible on the board (because playing it will be better for the opponent than for your own engine, given how many you'd be playing in a turn) or it'll be broken good with the price on a board with a discard attack, thus giving a large first player advantage if an engine is at all viable. Despite these potential pitfalls, I think it's worth testing. Side note - I'm not sure if the name is anachronistic, but it's clever.
Residence -- Is the +VP for victory tokens? Too easy to abuse and get into a stalemate with it. The same thing could be said about Monument, but it mitigates the problem by providing money to encourage you to buy something.
(PPE: pretty much what Qvist said.)
Coat of Arms -- If it's a treasure type, how many coins does it give? At $4, it needs to be $0 or $1 at most. Seems a bit on the strong side, but might be OK. This would make more sense as a terminal action though.
Hobo -- Wha?
Economist -- Extremely weak. Gaining copper is something you rarely ever want, and you certainly don't want to use a terminal action for so little value. The general concept is already covered by coin tokens.
Jailer -- With a few possible exceptions, the correct opening will almost always be double Jailer if possible. The curses will run out extremely quickly and then the rest of the game will be an unfun slog.