etyl second param

Common practice is to leave it out. Your setting of the template to add cleanup categories to entries using the prescribed format was done without discussion or consensus. Additionally, setting {{head}} to actually break when using the normal format (which is, by the way, added by numerous scripts) was also done without consensus. Forcing through these non-consensus-backed disputed breaking changes to templates that are among the most used on Wiktionary is completely inappropriate.

I don't think it's any more appropriate that you simply revert my changes without any discussion. I don't need to be educated. The normal format of {{head}} has never included leaving out the language code. In fact, after I made the change, I went and fixed the few entries that were missing one (there were less than a hundred). So your argument that things are broken by the change is completely unfounded, it seems like you're just being obstructive for the sake of it.

And adding tracking categories to entries is not something that needs consensus. Nor does it need consensus to change one valid format to another; people do it all the time when they convert, say, {{head}} into a language-specific template. Since having no source language on {{etyl}} and having "en" are both equally valid, there is nothing wrong with replacing one with the other since they are both equivalent. The only thing that would need consensus is to change the behaviour of the template so that the original practice no longer works, and while I do intend to suggest that at some point, I am not changing it yet.