for Hildesheim quite a few historical documents are to accessible online via FamilySearch, yet they are not indexed and mosty written in German Script (Kurrent). Often the images are of poor quality due to the bad condition of the originals. I listed the film-numbers as I don't know, if my links will work outside of Germany, but I'll give it a try:
Hildesheim Census Volkszählungen, 1809-1864 div. films (DGS) 7996100 8139071 8139072 8139073 8104033 8104034
Jewish Community of Hildesheim 1809-1815 (Napoleonic Aera in Northern Germany) DGS 007954696beginning on picture 844 of 1364 https://www.familysearch.org/ark:/61903/3:1:3Q9M-CS8H-89ZP-D?cat=652485
If you are searching for documents of Jewish Communities in Germany give this website a try: https://fs.webosi.net/ -> In the field (Globale Suche) you enter the name of the town -> the documents of the Jewish communities available are often labeled (Jüdische) Matrikel
I know it may be difficult, but you should give it a try. Good luck hunting!
