This is the key error
It indicates those paths you defined in the pipelines.yml are not found.. also You did not move the pipelines file did you?
Example, I'm sure you took a close look but could there be issues with upper or lower cases in the path.
path.config: "D:/Elastic/Logstash/7.12.1/config/logstash_sys_1.conf"
You can run the command with --debug and it should show you the paths it's actually trying to load and or give you some more detail.
Also If you try to run a a single conf file what happens
D:\Elastic\Logstash\7.12.1>bin\logstash.bat -f D:\Elastic\Logstash\7.12.1\config\logstash_sys_1.conf