While I think you should go about getting it fixed, I disagree on point above - I believe this error is not sufficiently material that IRCC would return the application. The identification of the parents on a wedding certificate is not consistent between jurisdictions (eg Ontario does record parent's names and province of birth, but no proof of this info is required; some European jurisdictions do not require/include parents' info at all on marriage certificates - I know because I just checked my own and does not have any info about parents).
So: I would submit as is and note that the parents' nationality is incorrectly recorded (in a separate letter of explanation), but that this was recorded mistakenly by the registrar without any documents about the parents' identity and is not considered material there. (Just like Ontario after all). Don't offer to get a new one (but do continue to try to get one from the authorities).
Now a warning: I could be wrong, IRCC might return it. You'd probably only lose two or three months - but presumably this is about how long it would take to get a replacement marriage certificate anyway.
