Suggestion

The 'Can See' condition only accepts Player and Player where in Spigot it accepts Player and Entity

New Syntax:

%players% (is|are) [(in)]visible for %entities% 
%players% can see %entities% 
%players% (is|are)(n't| not) [(in)]visible for %entities% 
%players% can('t| not) see %entities%

Why?

The more stuff you can do with a condition, the better

Other

No response

Agreement

• I have read the guidelines above and affirm I am following them with this suggestion.

I think you misunderstood. The method is Player#canSee(Entity / Player), so it's for checking if a Player can see an Entity or another Player. This is what the condition already does. It doesn't support entity sees entity, because that would need an Entity#canSee(Entity) method.

I don't mean entity sees entity, i mean player sees entity

the current syntax allows player sees player only

Oh my apologies, I mistook your "new syntax" for the current syntax!