To find the results of a RAM memory test (via the Synology Assistant app) you can SSH into your Synology box and run this command:
sudo cat /var/log/messages | grep Memtest
found this via reddit:
https://www.reddit.com/r/synology/comments/6jk40k/how_to_view_the_result_of_memory_test_by_synology/djxyah2/