I’ve had some nice coffee flavoured shisha. I’ve had a few, but in the last two or 3 years only Nakhla, since I bought theirs recently and its quite tasty.
If you have a shisha that is not up to par (I don’t golf) try adding some real coffee grounds or what is called Nescafe (I don’t vouch for that). Be brave and add any of these:
cardamon, muscat,nutmeg,cinnamon,or clove.
go lightly, especially on clove ,cinnamon and cardamon.
You could try vinilla or rum extract of the shisha is dry, otherwise you will make too drippy a mix and it will flow down the metal shaft.
Don’t forget the coffee jitters.