Did Dr. Ambedkar study Sanskrit in Germany?

No. He registered with the University of Bonn in April of 1921 to study Economics, not Indology. But he did not attend any lectures or classes so his name was taken off the University's books in 1922.

Yet Akash Singh Rathore writes - 'He also did a stint in Germany (Bonn and Berlin) to learn Sanskrit as he knew that doing so in India would have been impossible for him.'

Where did the idea that Ambedkar learnt Sanskrit in Germany come from? A German scholar writes 'During my fieldwork among dalits in Kanpur (Bellwinkel-Schempp 1998), I was often asked to give a speech, which I used to do with the introductory words, that I was born at Bonn in Germany, the town where Dr. Ambedkar studied Sanskrit. I had found the reference of a short, three months stay in 1923 in Dhananjay Keer's Dr. Ambedkar biography (Keer 1995: 49). My projection of benevolent German indology, transgressing the Hindu norms of reserving Sanskritic knowledge to the upper castes and caring for the dalits, was highly appreciated by my dalit audience'. However, the same scholar discovered that Amdekar hadn't actually studied in Bonn at all.  He writes- 'Dr. Ambedkar never took up his studies in Bonn. As he did not sign any lectures or attend any classes, he was taken off the university register on 12.1.1922.' Of course, Ambedkar could have studied Sanskrit in America or London. But he didn't bother. As the German scholar says- ' for his scathing attack on Hinduism as well as his most creative view of Buddhism he had to rely on translations and secondary sources'. 
This was by no means a disadvantage. There were some Dalit intellectuals and neo-Buddhists who had learned Sanskrit and Pali and so forth, but their lack of knowledge of English meant that they were less critical of Indian texts. The same German scholar has an informative article on Acharya Isvardutt Medharthi who is sometimes mentioned as an example of a Dalit Sanskrit scholar (actually he was OBC and had been educated at Swami Shraddanand's Gurukul) who helped Dr. Ambedkar study Pali. However, since this Acharya spent a lot of time, after retirement, going around conducting yagnyas, it is not obvious that he qualifies as a true Ambedkarite.

Does it matter whether or not Dr. Ambedkar knew Sanskrit? The claim made by  the RSS and people like Murli Manohar Joshi is that Dr. Ambedkar supported Sanskrit as the National Language. He himself, according to their narrative, was denied the opportunity to study it at the Government High School. Their meaning is that the Hindu revivalist schools, like those of the Arya Samaj or that of Swami Shraddananand would have eagerly taught Ambedkar Sanskrit. What the RSS wants is an India where everybody knows Sanskrit as this would tend to increase patriotism and reduce chauvinism based on caste or region. Ambedkarites, on the other hand, emphasize the English language as the true levelling agent. For this reason, I think they should let go of the notion that Dr. Ambedkar studied Sanskrit in Germany. After all, the thing is foolish. Germans don't know Sanskrit. If you study there, you should learn German or Sausage making or Beer drinking. Sanskrit can studied very cheaply in India. On the other hand, one should travel to Switzerland to buy bidis and Brazil in order to purchase paan.