Reducing training costs? So that those who already have several milions can be happy in the long term..?
Well, honestly I don't believe that any those options would "fix" economy in the short term. And it's indeed hard to fix it at all, and even harder to fix/improve it without changing code.
Economy means "dependence".
If the miners don't pay the warriors well enough, the warriors will not protect them. No protection = the "thieves" will come and kill + loot the miners income, thus they'll have less left as if they'd pay the warriors. (needless to say that a miner can't simply switch from "I'm a great miner" to "I'm a super warrior")
The more miners actually do mine, the lower will the price per ore be.
Miners also depend on people bringing food to them, otherwise they'll be too weak to be able to mine. So, paying some merchants. Merchants buy the food from cooks, cooks buy ingredients from "hunters". Hunters and "protectors" again need weapons which are made by smiths who buy the raw materials from miners.
If there are "too many warriors/protectors", they will of course get a low income. Too many miners lowers the income for them also.. and the same for "too many cooks" and "too many merchants" and "too many hunters" etc, etc, etc.
And
NO, there ought not be any "Warrior hunter mining smithy mage cook". Currently it seems like 95% of the guilds ought to change their name.. to something including "Mining" or "Miners". It's easy, "of"-guilds simply change it to "X of Mining", those who have a "X Y"-naming sheme, may try "X Miners".. etc... uhmm.. well, back to topic.
People need to get weak without food. People need to depend on each another (at least they can't do _everything_). People should be "more efficient" if they depend on each another. (More efficient = miner buys food = miner gets refreshed and can mine better again. Miner pays his warriors = warriors will protect them = less loss to the thieves.) Add some "boredom"-factor.
Lowering the "training cost" is a bad idea imho. It should rather be raised and Tria should rather be made worth less. (and easier to be obtained by not-mining. Maybe even be wiped to get at least back to some quasi-stable economy.) Some kind of "fix income / base income" might be interesting .. but that must be thought out very well.
Ileresa and Yadili earn, I think about 10 Tria a day.. selling apples and food. Why so few do actually buy, I don't understand.. if they're too tight-fisted to pay one Tria for an apple.. well.. they could even sell it again for 1 Tria - having no loss at all. Well unless you don't like to RP, because otherwise you'll lose your precious mining-time.
Edit:
For those who voted:
Reduce Platinum. It will not really change much, since the mining guilds (~95% of the guilds) already have their millions