I think I am not the first one to suggest this:
An action to allow me to save the SOL to a variable, an array or a tag to check collision using different SOL .
One of the issue with C2 is the difficulty to check collision between instances of the same object without knowing IID of UID.
I am working on a game with jewels and I find it redundant that I have to use an invisible sprite using 10-15 events (maybe not the best solution).