Color Replacement

Don't use the color replacement tool. As tools go, it's a sledgehammer (and I'm being diplomatic). I never touch it and don't ever intend to, and that's because I know how it works.

The immediate problem you're running into here is that colors have inherent brightness. That's how our vision works. Yellow is inherently bright, blue and purple are inherently dark. That's why you can't just translate one color into another. The term "color" as used in everyday speech is not very precise, it rolls color and brightness into one. But they are separate components of the visual image.

Instead of explaining, it may be better to just show it. The top right square is the yellow color, with the same brightness as the blue:

So you see, when changing from yellow to blue, you need to remap the whole tonality curve. Again - that's how our eyes work; not how Photoshop works.

With that in mind: the color replacement tool is useless. It has to work the way it does; if it didn't, it would just be a normal opaque paintbrush. The proper way to do this is to make a selection of the area you want to change, so that you can use the full range of Photoshop tools on it. Use the selection as masks on adjustment layers.