Hi Kathleen, you lucked out.
If the floor flange was cracked and was replaced this should be the buildings responsibility.
No matter what the material the floor flange was still part of the “piping” Installation.
I have gone to court several times over cases like this and you have a great shot at winning this issue.
This is waste piping should not be your responsibility for guarantee integrity.
This would be my PROFESSIONAL OPINION, ( by the way you should also be covered by your home owners insurance JUST like the building should also be covered by a policy)
Please keep me posted.