I'm not following the import of your comments.

Translucent phenolic plastics used to make imitation amber beads (from 1926 and later) are said to have been made in Germany, and are also said to have been brought into Africa by the French--and specifically through Morocco and Egypt.

However, all this is more anecdotal than historically documented. (As far as I know.)

I have no reason to believe these fake amber beads were in "German East Africa" sooner than elsewhere. And, in fact, I suspect the opposite.

In the 1970s, based on my observations, I suggested that oblate beads were more common in West Africa, and ellipsoidal beads more common in East Africa—and that the Eastern beads tended to be more often used as prayer beads, or in constructions that suggested a Muslim tradition.

If the designs on the beads you have shown were not burnt-in, how were they made?

Jamey