I actually just found out a way to have as many effects in a planet trait as you'd like. So, when Sorentoft mentioned schemas I decided to look at them (I'd ignored them because they looked very important). I opened up the PlanetTraits schema and found toward the end of line 31 that you could set the minimum and maximum occurrences of EffectModifiers. I set the max to 20 and saved it. Now, I tried to get the game to load my custom modified schema from the mods folder, but it didn't work. I modified the schema in the main folder to allow 20 occurrences of EffectModifiers, then started the game. I got to the main menu fine, and tried to start a match. The match loaded fine and when I moused over my homeworld it had every single effect I could find.
If someone could tell me how to get schemas to load from outside the main folder (like from Mods), that'd be great.