Think ! In what situations is the word illusion used
? It is used where there is a mismatch
between two information sources. (e.g. Visual image versus physical measurement). In situations of no
mismatch (including those involving social agreement), there is no "problem" and the word is irrelevant.
So your speculative computer simulation hypothesis is irrelevant unless you have "misnatch" evidence. It falls into the same category as pseudo-hypotheses such as "everything in the universe doubles its size every second". (If the ruler doubles its size there will never be a discrepancy).
Now it may be the case that "different levels of consciousness" (in meditation for example) give rise to different perceptions from the norm. Buddhists argue for example that "self is an illusion". What matters thereafter is how such cognitive states inform subsequent action or thought of the experiencer. The meditator may for example give up certain "personal goals" in an analogous eway to an enlightened desert traveller giving up his track towards a mirage of nearby water.