When writing my previous post (#2), it was over midnight for me, and I did make it too difficult.
Forget about entering any Concat numbers into 1st row of 2nd table. Design table headers as you want.

The formula you enter into B2 of 2nd table will be:
You can keep formulas in 2nd table. Whenever you edit 1st table, when in 2nd table the value of Index is registered, and there is enough Concat columns present, the changes are available in 2nd table immediately.