I'm trying to make a origin named Jester which goal is to trick my friends. So i decided to create a power which will make a large fog effect cloud of blindness. I've tried the command by typing it in chat and it works perfectly fine. So why is the origin not showing ? I've tried to launch the datapack without this power and it works. So where is the problem ?

If someone see what is the problem, please tell me !

The problem is that JSON has trouble parsing your command this way.
This is because the quotes (") are used to determine the beginning and end of a field in JSON, and in your case, the command also contains ". If you think about this like a machine, you'll see that the only thing which would be the "command" you specify is the following: summon area_effect_cloud ~ ~ ~ {Particle: (Everything from " to ")

To prevent this from happening, you need to escape quotes which appear in your command. You can do this by adding a \ before them: summon area_effect_cloud ~ ~ ~ {Particle:\"crimson_spore\",Radius:5f,Duration:200,Effects:[{Id:15b,Amplifier:2b,Duration:200,ShowParticles:1b}]}