Hello Tobias,
The point is that jhana citta is a type of a javana citta.
We do “bad kamma” (that lead to births in bad realms) and “mundane good kamma” (that lead to births in good realms) with javana citta.
– Jhana citta are a part of “mundane good kamma” because they also lead to births in “good realms”, i.e., Brahma realms.
We do lokottara kusala kamma (that lead to Nibbana) also with javana citta.
P.S. All “kammic energies” are produced in javana citta.