The 'two airplanes from April' rumour is from here:
Ryanair eröffnet Basis in Köln - airliners.de - Forum
The German forum people are highly sceptical about this. Esp with the new German flight-tax, and NRN already a very big hub serving basically the same area, plus HHN. LH would be very unhappy with CGN as they run the massive 4U hub there, which is effectively CGN's lifeline.
Nothing at all in the German media apart from some 'talks happening' between CGN and FR in October last year.
WW hastily got rid of EMA-CGN, but that's just WW's usual mess I guess, nothing deeper.