I have been told that churches are supposed to write on the back of the baptismal certificate the dates of any subsequent sacraments. What if the church doesn’t do this? Are records kept anywhere else, like in the diocese?
This is something of a misunderstanding. Each parish is
required to keep sacramental records and to notify the baptismal parish of sacraments of confirmation, marriage, and holy orders. I promise you, they
do keep these records. The bishop signs the sacramental register after reviewing it and it is required that he do so on a regular basis.
The parish keeps sacramental records in a sacramental register or registers. Our parish is small, so we have a combined register that includes baptism, FHC (which is canonically optional as far as recording it), confirmation, and marriage and death records. Other larger parishes have one register for each of these.
When someone needs their sacramental records, they are printed up (or hand written) on a form on in a letter and the parish seal affixed to the document. Typically parishes that are large have a template or form set up that they can go in and print the info up on. Sometimes the baptismal info is on the front and other sacraments are printed on the back. Personally, I don’t print duplex, I print a letter that lists all the sacraments on it and affix the seal.
Your personal baptismal certificate you may have received as a souvenir at your baptism does not have your other sacrmaents on it. That is why a current sacramental record must be provided, but it is not always in the form of a certificate.
If someone wants to get married and the other sacraments (first communion and confirmation and reconciliation) aren’t recorded, but they were known to be received, what is the person supposed to do?
It would be quite rare that they are not recorded. Something really exceptional. If for some reason there is no record-- such as a natural disaster, then an affidavit would suffice.
Also do you have to be confirmed to be married in the catholic church?
Yes, typically, although canonically there is some leeway that the priest has regarding this.