The x2 Rule

This is strange. This is one of the most fundamental rules of the language and yet there are two competing views on it. The worst thing here is that it seems it's not even being noticed that there are two views.

The rule I'm talking about is sometimes explained as:

(1) "If the x1 is empty, the first sumti after the selbri fills the x2, not the x1."

I don't agree with the above rule if phrased like that. In my opinion, the rule is much simpler and should read as follows:

(2) "Any sumti that appears right after the selbri fills the x2 unless the x2 has already been filled explicitly."

This rule has lower precedence than the FA rule ("A place that has already been filled is skipped"). And no, FA Rule is not a rapper (like Ja Rule, get it?). Rule (2) could also be phrased as "There is an implicit {fe} right after the selbri" (which also goes well with {be} = {be fe}!).

Here is how Rule (1) and (2) differ:

mi fi do cusku ko'a

Rule 1: ko'a fills cusku4.
Rule 2: ko'a fills cusku2.

Again, it seems both these rules are currently in use, which is quite strange indeed seing that they don't go together very well. I consider rule 2 much more useful and it's also simpler because it requires no additional step that checks if the x1 is filled or not.