Mmmm… according to https://www.nps.gov/kaww/planyourvisit/upload/Katahdin-Woods-and-Waters-Recreation-Map.pdf, the boundaries seem correct. (While this may not be a legal data source for changes, I think it can happily be used for arguing a "non-change"…)

If you know the correct location, may I ask you to just correct it? I am not from there and only help (among others) to fix boundaries which are structurally broken (such as missing lines which result in incompete relations).
The correct way to fix that is to move the points or to have the lines (ways) touch each other as they do now. If you need help doing that, feel free to ask again.
I try to move the line further to the North in the meanwhile.

The other one was incomplete as well, so I reverted this changeset. I hope you are ok with that.

May I know what was wrong with the deleted line here? Its deletion left the respective relation (T2 R8 WELS Township, 8439730) broken.

I don't know what was wrong with Gadingharjo (5615676) and Srigading (5615521), but this changeset leaves them broken. I fixed them in osm.org/changeset/61490921.

Could you please verify these changes? By moving some of these points, you made relation 114487 overlap itself. See osm.org/relation/114487 for details: in the south east, around "Brian Place", the two parts of the multipolygon overlap each other now.

An admin_centre must be a node, not a way. I hope you don't mind that I will revert this changeset in order to correct the issue.

You accidentally removed one line of the boundary relations. I restored them in the meanwhile.

I suppose it was a mishappening to change the whole area of Nikosia to a "site" and reverted this change.

Why? And why in this form?
If you have a look at osm.wiki/Tag:power%3Dsub_station, you can see
"Do not, however, attempt to automatically change occurrences of power=sub_station."

Sorry, that was a mistake. These should be separate change sets.
Why does JOSM still not warn about this?

Hi, it's me again:

In the changeset osm.org/changeset/60430470, I just added a segment to the line you created here so that it is connected to the way in the east of it.

Oh, I just saw that you created osm.org/way/604737876 in your first changeset. If you don't intend to create a longer route for mountain biking, it's just fine to leave it as it is – no additional relation required. But if it is part of a longer route, you should (or better: you may) add the said relation. (But if it is about mountain biking, better use route=mtb instead of route=hiking.)

osm.org/relation/103234 is a relation which describes the boundary of the municipality of Arsac. That means, it contains lines ("ways" on OSM language) which go along the boundaries.

You changed its attributes so that it no longer represented the boundaries of that municipality, but just a hiking route around that municipality.

As far as I understand your changeset comment, you tried to create a parcours (route) somewhere there.

The right way to do that would be to create a relation, give it the appropriate tags (as you did with the other relation: type=route; route=hiking, plus maybe a name for the route) and to add the ways which are supposed to belong to the route.

Welcome to OSM! For creating new trails, you must create new relations. Taking other relations and modifying them is not good, because these are gone then for their original purpose.
So I restored this one for now.

You accidentallc changed the attributes of a municipality's relation instead of creating a new one for the route you intended. I fixed that for now.

I restored the previous data now, hope that was ok.

So Ottobiano is no longer a municipality, but a horse route? I fail to understand that.

What was the reason for this change? Doesn't La Chaux-de-Fonds exist any longer as an independent community? "m" as a changeset comment isn't very useful for deciding this.

It's ok now, I fixed it, deriving the actual borders from the neighbouring quarters, especially Champagnat (osm.org/relation/8412628).