Not the whole story here; the changes do actually apply and can be subsequently used in battle, but there's just very few training options currently, so it's very difficult to increase values much higher than 30%, meaning you can really only train Forsaken that are nearly unbroken, or generated fresh via the testing tool in the Forsaken menu.
There are two potential goals of Training; changing a Forsaken's Fighting Style (What Circumstance damage(s) they do in combat and how much) and increasing their Corruption stats (which affect the costs and benefits of being used to fight or train)
To change Fighting style, all you have to do is use training methods that correspond to the damage you want them to deal in order to increase their Expertise; if you want a Forsaken to do Hate damage, you train Hostility. Each instance of training gives Expertise to the corresponding Circumstance, and you get bonus if a different Expertise is already very high, even converting Expertise in the opposing stats to compensate and help you re-spec well-trained Forsaken quickly.
When their Expertise in one or more stats gets high enough to overshadow the remaining stats, and are also close to each other in value, you'll get an event pop-up telling you and they'll change their style to deal those damage types, and they'll gain a small damage multiplier to each damage type for higher Expertise.
If you want to Increase Corruption, you have to overlap multiple different training methods to increase the Training Intensity of the Corruption stat you want to change. The total intensity starts at the value of the most intense method you pick, and goes up 5 for each extra. (if you want to raise Hostility, and you choose two methods with Hostility 20% and Hostility 15%, the total Hostility will be 25% regardless of which order you pick them in)
Forsaken won't want to consent to actions that are too intense, but are more likely to do them willingly if they have high Obedience or they are familiar with it (they've done the training before), but can always be forced into training by using at least one action that increase Obedience.
If this total Training Intensity for a given Corruption is equal to or greater than the Forsaken's current Corruption + Half of their Deviancy, they will gain Corruption and the stat will permanently increase by a small amount. They also gain an equivalent amount of Obedience if you forced it on them.
There's a few more subtle complications to this system; like each training action having a positive and negative to subsequent actions in the same session, but it's difficult to make much use of these with the limited set of training, and this covers the basics of how it works. It'll become much easier to do once we can pick multiple higher level options that target the same Corruption, as they'll stack up much faster that way. This also creates various strategies for training; high Deviancy Forsaken could train hard and gain a lot of Expertise without raising their corruption, high Obedience forsaken could be trained extremely intensely to high corruption, etc.
Currently Suppressors deal 1 circumstance, and all 4 types of Trauma. To a certain degree, you do want to cause Trauma anyways since that's going to create new openings for you to continue dealing Circumstance damage (and also raise angst to increase damage and EE gain), but the issue lies more in the fact that while each circumstance type also raises their corresponding trauma, that Trauma also
reduces the circumstance that just increased it.
eg; Hate 2 gives 2x Circumstance, but also 4x Fear, and each level of Fear causes 1/2 Hate. Given even relatively equal damage values, Fear will rapidly eclipse Hate and you'll do little to no damage in Hate, but also pick up 1-2 levels of Disgust, Pain, and Shame, now dealing x2 / 4 = 1/2 damage, reducing all further attempts to deal Circumstance of any kind to them. The outlier is Injury, since it's multiplier to itself by increasing circumstance is higher than its multiplier to Pain (x4 and x2), so it gets "ahead of the curve" and allows you to start building higher numbers.
Which is to say; an Ambush with a Suppressor that deals most damage types other than Injury are not only less effective than general commanders, they are often even detrimental. Expo can also be okay if the duration is quite long and the other chosen are Friends; you can set up bouncing Expo damage multipliers between them to compensate, but because of the opening requirement quirks, it becomes hard to generate a second opening on the same Chosen and you can sometimes be left dealing too little damage to create any new openings for the rest of the fight. Hate and Pleasure suppressors very quickly run themselves into x0 circumstance without actually dealing much first, and need a lot of Expo done to another Chosen to try and recover from that state.
I think the more potentially strategically valuable way to use Suppressors is with Patience after T1 breaks. If you are trying to get 1 specific type of damage into a T2 or T3 break zone without raising the others too much. It lets you get around the Tactics damage reduction for dealing only 1 damage type without resorting to Defilers, but it's only going to work in quick bursts with the proper support, or the multiplication is going to get out of hand. Even still though, I think a generic commander is still more useful in most cases, since in the same amount of turns you can start with some Injury and Hate to get the ball rolling, and once you've got multipliers going you can move to the stats you are trying to increase.
3 turns of Plea suppressor might result in something like, 250 | 500 | 625 Pleasure. (x1 x1 x1/2)
3 turns of a basic commander could be more like Injury 100 | Injury 500 Hate 400 | Injury 1300 Hate 1200 Pleasure 800. (x1 x4 x8)
