Self-referential systems behave very differently to "normal" systems. Douglas Hofstadter has made a whole career out of analysing them. In his famous book Gödel, Escher, Bach he compares the self-referential patterns in Escher's art and Bach's music to Gödel's Incompleteness Theorem and the philosophical revolution it brought to the study of mathematical systems.
Fortunately humans have come across this challenge before. There are three major fields which all contain self-referential structures, and each of them can shed light on how to deal with financial modelling.
Language. This statement is false. Or in its original, 3000-year-old form, Cretans are always liars - or at least so said Epimenides, a Cretan. Language is a very fluid medium with few strict rules, but the addition of statements which talk about themselves makes it even more unpredictable. The linguistic equivalent of Glass-Steagall is to ban simple statements like This statement is false; but this victory only holds until someone discovers that an economics professor can still say "The economics profession right now is useless" and thereby impugn the logic of their own claim.
Software. Unlike mathematicians and linguists, software developers actually have to make something work in the real world. So they've been obliged to find ways to build and control self-referential systems without destroying the world. Software is self-referential because software code resides in memory, and also has the ability to change whatever is in memory.