Your client has to withdraw all the prior missed RMD's now, and don't forget the one for 2023 (that can wait until 12.31.23).

If your client is charitably inclined, this might be the time to do a large charitable contribution directly from the withdrawal(s)

ALL the amounts will be reported on one F 1099-R for the year 2023.

F 5329 will need to be completed (maybe one for each year?  I'd have to read the instructions...)  The F 5329 can be filed separately from the F 1040

My experience is to NOT compute the penalty; write up long *sob* story explaining why the RMD's were missed and what has been done to make sure they won't be missed in the future.  It's much easier to get someone at the IRS to forgive than it is to find someone to refund the penalty paid.

By "gold", you mean the retirement assets are actually/physically gold bars/bullion/coins???