Leopolds have keycaps in Cherry profile. The red or black O-rings sets you could buy are better for OEM profile that have more space in-between switch top and struts inside the keycaps. With Cherry-profile keycaps, the O-rings would impede too much of the key travel.
Instead, for Cherry-profile keycaps do get Orhodontic elastic bands 3/16 Medium". These white/translucent rings are thinner than the black or red O-rings and don't impede key travel as much but are just as good at reducing noise and are just as inexpensive as O-rings.
These orthodontic bands are too thin for OEM-profile keycaps, however.
Another factor is that noise can be transmitted to and amplified by the desk the keyboard is sitting on. Once you have installed dampening bands you could try one of those super-wide mouse mats (more like desk mats) underneath the keyboard and see if the noise is reduced when using that. It does make a difference for some of my keyboards that don't have good-enough rubber feet.
I have seen Cherry MX Silent Red switches in TKL keyboards from Filco and WASD Keyboards. Filco calls them "pink" because the slider has a slightly lighter red colour than in regular Red switches.
WASD Keyboards does however have a reputation of their keyboards being a bit loud because of how their case is constructed.
Both Filco and WASD Keyboards come with thin OEM-profile keycaps with low-quality printing that (in case of Filco, anyway) rubs off too easily, so you might want to replace those with some thick keycaps. Filco keyboards also have no frills (media keys, etc.) whatsoever.
The switch was developed together with Corsair, but I can't find any TKL from them with this switch.
I have yet to test one of these switches myself, but I have been told that the switch should also be smoother than the regular Cherry MX Red.