Carsten
As everywhere else, focus in the past has always been on fighters, fighters and again fighters and you could also add units to that, ie fighter units.
As far as I know there is just one book written about a German bomber unit in WW 1, Kasta 23, but a pretty good place to start is this one
http://www.frontflieger.de/2alb.html
It does not state aircraft types vs units, but at least it will you some degree of the German organization and also a time frame of their existance.
Checking Kasta 27, you will see it did not operate any aircraft in 1917 at all since on 1.1.1917 it was re-named/designated Schusta 9. Since it formed very late in 1915 it existed basically only one year, 1916.
Also note that Kasta 27 (1916) was not the same as Bosta 27 (1918)
Schusta 9 operated LVG C.IV in April 1917 and if they did so as Kasta 27 in 1916 is something I don't know.
Also looking inside Cross & Cockade (old issues) I fail to locate a single article about any KAGOHL/Kasta unit. I seem to remember there have been articles about bomber pilots (or crew members) but it would take ages to go through all of that.
Cheers
Stig