Maintenance of unauthorized/unsanctioned/illegal/whatever trails

What's the etiquette for this when you're not the builder and don't know who is?

For the record, I was hiking this fairly obscure trail recently and noticed a lot of minor blow down (the type that won't stop you riding but has high potential to wreck your derailleur).

I know that branches are often used to disguise the entrance/exits to trails but this was much more than just that. But, other trails in that area don't seem as affected so I can't tell whether it's deliberate or just a symptom of lack of use of the trail.

As I'm in that area hiking occasionally, I was gonna clear all the blow down except at the very top and very bottom of the trail.

Is anyone likely to give a fuck if I do this? If so, how do I get a message to the builder?

Ha very timely - there's a few sections of a trail I use and love (and would love to help on) but without some extra planning for runoff it will turn into an unusable swamp.

It's not that hard to find the builder/maintainer of a trail.  Just have to ask the right people, probably 2 degrees of separation at maximum.  Clearing rocks, sticks and cleaning drains doesn't need permission and should be encouraged by the builder.  Probably anything more than that should be a reach out.