Were Red Lightsabers supposed to denote evil? Because I swear in the EU red meant synthetic and the reason the Sith used them was because they didn’t have access to natural crystals.
In the pre-AOTC EU, lightsaber colors don’t have any meaning. In fact, Leia has a red lightsaber in some books and some of the Jedi on the council in TPM had red lightsabers.
When George explained the meaning of lightsaber colors to Samuel L. Jackson, the EU introduced the synthetic crystal lore to explain it in-universe. However, Shadows of the Empire established that Luke’s ROTJ lightsaber has a synthetic crystal, so we know that synthetic crystals aren’t inherently red. My headcanon is that the Sith make their lightsabers red to honor the Sith species.