Only user facing changes are documented via werks. This is not always done consistently though.
If we document each change in Checkmk, then you will be drowned in non-valuable information.
The good thing: you can read all changes in Checkmk here:
So, we are not hiding anything 
No need to do so. Have fun reading the 200+ commits per week. In the week of Sept 7th, there were 752 commits. So, enjoy.
Updating dependencies is something we do on a regular basis.
Example: cmk-frontend: update dependencies · Checkmk/checkmk@5d46fb9 · GitHub
You search for “bump”, “update”, “dependencies” in the commits.
Or search the respective bazel module files or packages.json for stuff like npm.