Intro
My team and I have found an interesting speech/lecture by Dr. Gerdien Jonker, Ph.D on the Lahori and Qadiani missions in Germany and other parts of Europe, she focuses on Germany and the Lahori-Ahmadis a bit more then their Qadiani counterparts.

She has additional and new work forthcoming

http://www.brill.com/products/book/ahmadiyya-quest-religious-progress
​Research projects 

2016-2019: Ahmadiyya Mission in Interwar Europe (2) (DFG, Bonn)

2013-2016: Ahmadiyya Mission in Interwar Europe (1) (DFG, Bonn)

Dr. Gerdien Jonker, Ph.D was invited to the Lahori-Ahmadi Jalsa in 2013 and gave this presentation
It should be noted that Dr. Jonker gave her research work in a lecture at the annual Jalsa of the Lahori-Ahmadis in 2013

The video

Other related essays
https://ahmadiyyafactcheckblog.com/?s=inter+war