Caused by: org.gradle.internal.resource.transport.http.HttpErrorStatusCodeException: Could not GET 'http://files.minecraftforge.net/maven/org/eclipse/platform/org.eclipse.equinox.common/3.18.200/org.eclipse.equinox.common-3.18.200.pom'. Received status code 422 from server: Unprocessable Entity

Since yesterday I'm keep getting this error (Baritone 1.6.5 version)

Also Im tryna change modid. Is it actually able to change?

1.16 is no longer supported so might be the build broke. If it's the maven you might want to try using another maven repo.

Baritone should be fine with you changing the modid. Meteor does it routinely to distinguish their built in versions from upstream Baritone.