The chat in FeralHeart is limited to standard English keyboard layouts. If you for example have another layout the way you enter these symbols will not always work depending on how they are entered on the specific layout, in fact it might even crash your game at times, not fully certain if this is your issue but I thought it could be worth mentioning.
If this would be the case for you, the only fix would be to change to to standard English layout for your keyboard, I do believe (US) and (UK) both should work or at least have it so you can swap them on command when playing the game.
If this wouldn't be the case for you however I'm not quite certain what could be the case, it tends to lead down to which layout you're using for your keyboard when certain symbols do not work or game crashing due to typing. I myself must go into English layout just in order to make "^" on mine, pressing a key not even related to the symbol just because the other layout has it that way.
