Your reports are a bit different than ones I read in the states. No surprise there, but it does throw a bit of confusion when I read it. But you do live in a very civil first class country so that should help your confidence!
If I'm not totally off, I see water that is watched carefully by a first class operation. All things appear to be good except for occasional manganese running too high. Lots of mining in the area, maybe? You have chlorine rather than chloramine so you could likely get by with just letting it gas off rather than chemical treatment. Whichever works for you. Water PH varies from slightly above neutral to slightly more alkaline but still very reasonable. Likely pulling from different water sources at times??/
It does look like you have quite a lot of minerals GH/KH in the water. That is where I would think the white film is coming in. If you were to let the bucket dry, I might guess you would find a white film something like chalk or cement scale? If it is a real bother, I might try adding an airstone to the bucket to get more movement and air to the water. I would leave it open top if there is not reason to cover it like kids, pets, etc. I get much the same film in my reserve water barrel and at times enough piles on the bottom to turn brown if I don't stir it now and then. More yuck factor than real problem.