Coffee isn't as bad as beer in the keyboard, especially if there is no sugar in the coffee.

I used the wrong powder once in my first .375 IMP., years ago when I was just starting into the realm of wildcats.
This resulted in a pressure excursion which actually melted part of the ctg. base & spewed molten brass onto the bolt face & blew the bottom metal out of the stock.

The ctg. extracted normally, not even sticky in the slightest.
Of course, it was in a Mauser 98 action.

The only time I have ever had sticky extraction in modern ctgs., was with greatly tapered, inefficient and poorly designed cases like the .375H&H.