There is no separate Catchup amount. They are treated as one unit, so there seems to be an extra $1,000, which is 6% penalty, which is $60.

There also is no such thing as a Joint HSA. The Account is owned by the account holder, which is typically set up per the insurance policy which qualifies.

Try this topic to see if it helps you understand:

https://www.peoplekeep.com/blog/how-hsa-contribution-limits-work-for-spouses