After checking with the Riga City council, was directed to "Jaunciema attīstības biedrība".
https://www.jaunciems.lv/
Notice the logo there... :)
Checking with that society, the posts were deployed last year. Routes are not marked yet, and they do not have any GPX traces. Marking of the first route expected to start in September.
Worth keeping this note open, as we might be able to get some of the rotes in soon.