Please note that footways/sidewalks should never end at the edge of roads, Instead they must connect to the road. Otherwise they'll be useless for routing.

What was the warning? Also note that supermarket details has been moved back onto the building

The windmill was allready tagged as windmill, so to avoid duplicates I've removed your version.

Jeg lavede det om netop for at undgå konflikter i validatorerne

You're using the latest "tested" version. The warning has been removed from the development version and the next "tested" will not report it. See https://josm.openstreetmap.de/ticket/17901

Please note that the cycleway warning due to complaints has been removed from newer versions of JOSM

Welcome to OSM and thank you for your contributions. Please note though that the name-field should be used only for actual names, not for descriptions like "Spielplatz" or "Parking". I have corrected your contributions and was lucky to find an image of the memorial stone, so I could complete it :-)

I hvilket program?

Yes, you shrunk the house to fit older imagery (as can be seen from https://overpass-api.de/achavi/?changeset=72531206). Looks like the house was extended southwards sometime between the Bing imagery (capture date 2012) and spring 2018.
Looks like another mapper reverted your change a few hours ago though.

Ok, men derfor er det stadig tilrådeligt at være forsigtig med at tegne skovveje efter Kort25, som det ser ud til, at du har gjort visse steder. Det er generelt bedre at kigge på SDFE luftfotos eller terrænskyggekort

Please note that the imagery you're looking at (Bing) in your editor is several years old and that never imagery (SDFE) shows the house to be larger

What's the actual name of this second hand shop? Hint: never use descriptive names.

This one was mapped already: node/2292140030 , so I've removed your version.

Please note that I have removed this "bookmark" from OSM

Jeg tror du skal være forsigtig med at basere indtegninger på SDFE kort25. Det ser ikke ud til at være alt for opdateret

Please note that I have removed this "bookmark" from OSM

Der er tale om en angivelse af hvor der engang i 900 årene stod en palisade, så jeg synes det vil være osmviborgs forslag vil være lidt misvisende/ikke aktuelle.

Bemærk også at rutevejledning via arealer ikke fungerer

Hvis du genopretter betonfladen, vil jeg anbefale at du helt undlader at røre stierne.

Bemærk også at når du ændrer til area:footway er den ikke længere synlig på standardkort