well thx for the pic, it always helps a lot.
the washers on the board with the screws are great as it is a stable construction vs slippery application, and it does surpress vibration from the board.
That said, vibration from the floor will also easily travel and spread into the board.
imho, you got 2 excellent options to get it solved.
both ways you add a second board on top, same material, laminated together with bucky nanopaper inbetween.
option a you make holes in the seconds board where the rods are and then place the component on top.
The buckypaper will destroy vibration from below and from the component actively,
b, you make holes for the rods and the footers for the components.
The components are still sitting on the original board and the buckypaper works passiv as dampener.
best is b with a third board under the original board, also laminated with buckypaper.
The footers will be surrounded top and bottom.
All that said, avoid multishelves/tall racks. Singleplattforms are far superior if heavy enough