Nothing to do whatsoever with Germany or Russia.
The Siamese Government ordered these - along with Arisakas - from I believe the Nagoya factory in Japan. They previously and concurrently used the British Lee Enfield SMLE III* (as the King of Siam was military schooled in England). These were used right through until the Japanese surrender in Thailand, and continued to be used after alongside contract Arisakas and Arisakas left behind/surrendered by the Japanese.
The elector pencil serial number is importer added, as the original serial number is in the Thai script, and I believe BATF import regulations required a "translation" of the script, or at least the addition of a trackable ENGLISH serial number. Might not be import marked, but is import compliant.
Interesting rifles, but not a thing German apart from a rudiment design basis, and definitely no Russian association. Common as mud here in Australia, and prices are still low (unless on the online sites lol).