I have decided to not count the Star Cards released during the show's original run as canon on here any more, there's just too many discrepancies with them. I've also found that most fans pay them no mind. While my current main focus is character bios, I'll be going through and deleting birthdate information included on the Star Cards since this seems to be the biggest problem with them.
The biggest change so far is Mrs. Tremond's grandson, the article formerly known as Pierre Tremond. The name Pierre is never given in the show or film, only on the card, which also seems to assume he is not a spirit.
Despite the non-canon status, I may add all of their information in a separate part of each article, but I'll decide on that later when I've got the manual of style together.
Therefore, the only characters who have their birthdates confirmed as canon are Dale Cooper (stated in The Autobiography of F.B.I. Special Agent Dale Cooper: My Life, My Tapes, which I assume to be canon in every aspect that isn't contradicted by the show and film), Dougie Milford (shown in The Secret History of Twin Peaks teaser, which is canon), and Margaret Lanterman (also shown in the teaser).