Colour, dyeing, pigments etc.

[Martin Moser]

Also, they look orange to me.

Yes, that's what they look like on my monitor as well, they are a shade more towards red though actually.

Most likely, red leather was more like bronish red or maroon. The trouble is, dyes are transparent, and leather is brown to start with, usually.

True if you use brown leather. Alumn tanned leather is white, so you don't necessarily get a brownish red.