In 2300AD they are still a German colony, albeit with a great deal of tension with the controlling nation. As a colony settled by a French-allied nation, their relationship with the Manchurian colonies is, at best, strained. Heidelshiemat shipping tends to suffer a great deal of harassment as it passes through Manchurian-controlled space. Even with German control, they are still a European colony, and not suffered gladly by the major power in the region.
In 2320, the focus of support by the German government on the French Arm has convinced Heidelsheimat that it would be best to go it alone. It is possible that they would get tacit support from the Manchurians in this regard. From their standpoint, it is better to have an independent, but weak, Heidelsheimat, rather than a colony enjoying the full support of a European power. Given the destruction wreaked along the French Arm, Manchuria may even be concerned that the focus of exploration and colonization will shift to the Chinese Arm, especially as the Life Foundation 'bridge' allows ships to bypass much of Manchurian-controlled space.