I have a couple of suggestions for Latvian records.
The following link takes you to a database that holds the translations of some of the rabbinate records from the Latvian State Archices. http://usdine.free.fr/thexrigaxvitalxrecords.html.
Try the Latvian State Archives. The rabbinate records are sometimes easy to browse because the entries are in the Roman alphabet and the names read very similarly to English. Sarah is Sarah is Sara is Sora. Same for David or Isaac. The entries are also there in block scripts (I believe Hebrew but possibly Yiddish).
Antra Celmina <admin=celmina.com@...>, a Canadian of Latvian descent, offers a course in how to maneuver the Latvian archives. First course is free. After that the costs are fairly minimal.
The Latvian archives are on Ancestry but not searchable. You need to browse.
I share this because I found my grandfather's brother's birth and circumcision record after searching for years and from that record uncovered my great grandfather's place of registration in the Russian Empire and now have more places to search. Everybody seems to concentrate on Poland, Ukraine, Belarus. I assume that is a matter of numbers. Latvia was a much smaller Jewish community. But there are records.