Why not Roman blinds? Roller blinds with fabric laminated to them for color and pattern?

I wanted to hide the ugly cut corners somehow. Do you think this can happen???

You can hang roman shades on the window trim or just move the rods up to the top of the trim. Where you have them now looks weird and the ones on the other wall, also

Blinds or shades installed inside the window trim is probably your best bet. I say this because there’s no good space for the drapery return to go. Swept to the outside like in the photo just draws the eye to the slanted walls on each side. There’s not enough room to sweep to the inside because the fireplace is right there.

Shades or blinds are perfect for this type of window. Drapes will not make the wall look taller.

If you continue the line of the curved, pulled-back curtain up to the ceiling, I think it does make the room look taller. I'm not sure how you would attach the curtain along the sloped ceiling, but I have seen it done. You could then experiment with exactly where to tie the curtain back; if you hung full length drapery, you could tie it back lower.

In all cases, however, you need to be certain that curtain will not come too close to the fireplace. For that reason, shades may be a safer choice.