[firebrand]

The Catholic church has no concept of illegitimacy. That’s a secular legal term.

If the father is unknown, or “unknown,” the baptism certificate says “pater ignominiam,” father’s name unknown, if I have the Latin right—this is where our word “ignominious” comes from.

[Campion]

Canon law pre 1983 had the concept of illegitimacy -- it was an impediment to ordination to the priesthood -- but the children of a putative marriage (one entered into in good faith by at least one party) were always considered legitimate.

Post 1983, you are correct that "illegitimacy" does not have any meaning in canon law.

[Salvation]

An annulment only says that the marriage was not the Sacrament of Matrimony. The marriage is NOT illegitimate.