Calling method which takes interface and delegate as argument

[divided43]

in il2cpp game i have function like this:

System.Int32 FLIMPMHGLDE(System.String MFLDKAEFHBE, Google.Protobuf.IMessage PLEJOGKIBKM, System.Action PKJCIFGCNLN, System.Single HAOJFNBEMAP, System.Object CIKHIMLPLLH);

I want to call method like this to send something to server. I've founded class of IMessage and able to edit fields there. When game calls it by itself, it takes object of packet with edited fields and im getting what i need;

Now i want to call it myself, by clicking on custom button for example;

Not sure how need to correctly work with delegate and interface argument, and in general call method like this. with .inflate?

il2cpp bridge says this is non-static method, so i have to call it with Il2Cpp.Object, not a Il2Cpp.Class; but when i try to put "this" as argument, it says method takes only 5 parameters, not 6

Doesn't signature looks like in generic methods?