It seems that 22kg allowance is now standard on bmibaby flights per their FAQ baggage section, the website hasn't caught up and the 22kg special offer says until the end of Jan. That's the benefit of airline competion I guess and in this case we have Jet2 to thank, I can't see Ryanair following suit tho?
Both MUC & CGN are also still in the drop down date menu until the end of he Summer, not sure if it will allow you to book them though?
Regarding the baggage it still states for all new bookings made untill the end of January. However as you have seen, it will be good to see at the end of January whether or not they go back to their 18kg standard allowance or the 'book before end of Jan' is just marketing to help hurry bookings.
As for CGN & MUC, unfortunately despite them being in the timetables throughout the summer they do end in March and May respectively.