When is it not okay?

I use Aperture to catalogue and do basic editing of my pictures. Unfortunately Apple have stopped development of it and when I update the macOS I won't be able to use it.

I started looking for an alternatives; the Adobe suite would be ideal, but it's too expensive for occasional and basic use.

There are many free applications, Darktable is well reviewed. Once installed it was too difficult to use, I had to search youtube for even basic how-to's. It has to be the least intuitive piece of software I have ever used. You should be able to at least get started and do basic tasks without the use of google. I gave up; I'm sure if enough time was available I would discover incredible results.

I have Affinity Photo for more advanced editing, again I couldn't justify the cost of Photoshop.

I am now using Luminar 4 to import and edit my work, so far I'm impressed. Youtube has taught me about some of its many features, but I worked a lot out for myself. It uses AI, (artificial intelligence) to speed up some processes. I still do the basics, but I can now do much more than I could before. 

This has lead to a dilemma; how much manipulation is too much? I want the results to look natural, this technology can allow massive changes to be easily achieved. Take the next two pictures for example. The first is from Aperture, with the sky over exposed. When I took the picture there was more cloud detail. The second image was the result of Luminar AI making the sky easy to replace. It's not what I saw at the time, I added a stock example.

Is the second picture too much? 

If I upload it to Instagram, Facebook, or my website should I label it as manipulated?

Thinking about it now, I could have taken a second picture, exposed for the sky, then combined them. Would that have been more valid?