My idea for balancing jarate is to divide the soaked time by the amount of players hit. For example, if I hit 4 players with 1 jarate jar, they would each have jarate on them for 2.5 seconds. Please tell me if I'm dumb, but i think this is alright.
Edit: same concept with mad milk
2nd Edit: Also for the machina, if valve made the rate of fire and/or reload time slower, then I think it would be more ideal and fit the playstyle that most 6s sniper use, which is to just charge up and and go for one pick. At the same time, its downsides may make another player not use it, making it kinda balanced.
Ofc these are going to have to be made by valve. :(
just my two cents