@matti, you can actually have links with spaces in them if you include them in angle brackets, like this:
[2020-02-10 - FacileThings](<2020-02-10 - FacileThings.md>)
I believe this is even CommonMark standard. Without the angle brackets, the document would not follow the CommonMark or normal Markdown standard and therefore not be usable with other Markdown editors and tools.
However, I think Obsidian should provide some support for adding either angle brackets or urlencoding automatically. The angle bracket syntax has the advantage that it is more readable, the urlencoding has the advantage that is is even more compatible. So it would be best to make this configurable.
This should also both be supported by the “paste URL into selection” plugin. I already created an issue for this.