First of all, sorry for not noticing your post earlier.
Well, the hitting things I made follow the standard rules for splash weapons. So a thrown character has a range increment of 10ft and absolute max range of 50ft (+/- 25ft from deviation on a miss) without the Far Shot feat.
But indeed, allowing the automatic hit against another opponent 5ft away was not my intention, need to change that.
Another thing I've been thinking on has been to, instead of making a thrown character a splash weapon, make them normal ranged weapons with a range increment equal to the throwing character's reach.