Hi Frederik:
We should exchange brain waves or something (Vulcan mind-meld?). I have learned a lot about chords, scales and theory (informally which I will explain in a moment) but find myself really challenged using the computer to create the kind of wonderful sounding tracks you shared recently.
Sometimes we get to a point of frustration because we are ready to learn something more advanced. Sometimes it is something we did not want to learn before and sometimes it is something we did not think we could learn. I never thought I could fingerpick on the guitar, now I play "Dust in the Wind" for anyone who will listen.
Let the frustration drive you toward a new frontier. It is very rewarding.
I'll tell you how I learned to play keyboard to some extent. From that maybe you will see a way to attack the problem. When I was about 10 or 11 I started doodling on the piano. As you know you can do a lot with just the white keys. Also if you play just the black keys you are using a pentatonic scale (there's some theory for you).
While doodling I found a large printed staff with notes on it that my sister had from her lessons. It sat on the keyboard behind the black keys. When you line up middle C, all the keys of the piano are shown on the staff. Then there was something that had simple major chords written on the staff with their names: F,G,D,C etc. When I played the three notes of each of these I discovered that the distance between the first two and second two notes was the same no matter where on the keyboard the chord started. Pretty quickly I noticed that C, F and G all have the same fingering. Another group of chords with another fingering was D, A and E. You are probably way beyond that but bear with me because I'll get to something useful soon.
Because I had already used a self teaching book to learn guitar chords I was familiar with the chord letter names and with simple lead sheet showing the chords as they occur over lyrics to a familiar song. I found that just as I could sing the familiar tune and accompany it by strumming the chords on a guitar, I could do the same thing with the piano. Because I like to sing, it became a very powerful expression for me personally. The songs I started with were very simple ones like "My Bonnie Lies Over the Ocean" and so on. But after that I was doing the same thing with Beatles tunes. That is when I started learning that chords had variations like sevenths, ninths and elevenths and playing through these you end up with strong musical lines in support of the melody. The point is that somehow singing with the chords and rhythm made it come together in my head pretty well. This did not give me any technical skill, that comes with real practice and discipline, but I gained the confidence I needed to move on. Next thing you know I was learning how to transpose keys and modulate from one to another because the spatial (don't know the technical word for this) relationship of notes within one key is the same as that within another, they are just shifted up or down. So forcing yourself to change a key helps you become broader in how you can approach your music. Once you are familiar with chords to accompany yourself singing, take time to use someone else's melody to figure out the chords that go with it. The more you do that the better you get at choosing alternative chords for your own pieces. That in turn means you will find other possible harmonies that are not heard the first time you work with a tune.
Then start playing progressions of chords up a scale. Play C major (C, E, G) then play the same fingering on the next note up (D) which is D minor, and go on up the scale. The chords are C major, D minor, E minor, F, G, A minor, B diminished and you are back to C major one octave higher. When you can do that in just one key you have made a great step forward. Now do it in all the keys, simply by starting on the first note of a scale. The piano is excellent for visualizing these things (the guitar is not!). This may sound a bit silly but doing this I learned to play chord progression in all the keys. After learning one simple scale I forced myself to play it in all the keys as well. Do the major scales , Then do the minor scales. Then do the alternative minor scales. You just keep building and it will become intuitive as to what you can do with these in your own pieces.
When I get some software that can create MP3s etc. I'll post some of my pieces. My first attempt with my old software yielded a 35mb .wav file of a 3 minute song! They are not world class but they demonstrate application of what I learned from this and from listening carefully to the structure in other composer's works.
Good luck!
Ken