@Greg ********
In simple terms:
If you married outside of Thailand, you must first have your marriage legalized through your embassy and then the Thai Ministry of Foreign Affairs (MfA) before you can obtain a Kor Ror 22 marriage certificate from the civil registry office (Amphur).
If you married within Thailand, you do not need a Kor Ror 22 to prove your marriage. However, you can obtain a Kor Ror 2 from the civil registry office.
If you married outside of Thailand, you cannot obtain a Kor Ror 2 certificate. A Kor Ror 22 certificate is required to prove your marriage.
Now, let's assume the marriage took place within Thailand.
In this case, your Thai spouse simply needs to go to the civil registry office (Amphur) with their national identity card to obtain a Kor Ror 2 certificate.
This is the standard marriage certificate for marriages performed within Thailand.
... The cost is 20 baht. For use within Thailand, legalization by an embassy or the Ministry of Foreign Affairs is not required.
The original marriage certificate with the rose border, which you received when you married within Thailand, is called a Kor Ror 3.
Unfortunately, it is not accepted by immigration for renewal applications, as one could be divorced and present an old marriage certificate to gain an unfair advantage.