OK I found a problem in World.d.ts that’s why i cannot registerSystem with attributes without intelisense errors :
registerSystem<T extends System>(System:SystemConstructor<T>): this;
it’s a shame because the functionality is here 
in the World.js :
registerSystem(System, attributes) {
this.systemManager.registerSystem(System, attributes);
return this;
}
So it works, but intellisense in VSCode with ecsy is bad currently.
I made a PR to fix this problem.