What is this part called and where can I buy one? (frame with mouse buttons, part of T520 bezel)

[simplify]

Not seeing a way to post images... -> https://imgur.com/a/ccazjzh

It's the frame around the touchpad and two frontmost mouse buttons on a T520 and it's attached to the keyboard bezel assembly. I want to get a replacement and don't need the whole bezel, I only need what's seen here but I don't know what it's called or how to find the part number. Also looking for recommendations of where to buy this kind of thing; I've never bought anything more specialized than a battery or RAM; never any parts per se. I checked the Lenovo site and they have barely any parts at all for T520s and certainly not this.

Left mouse button was removed when I took the photo but that was only for cleaning. After cleaning it's still little erratic and sometimes you have to press a little hard or more on one side of the button. I have no idea if the contact can be cleaned more assertively or do they at some point irreversibly wear out so I thought I should get a backup of this whole thing in case they finally wear out.

[RealBlackStuff]

Nobody sells just that "frame" (for lack of a better word).
The X220/T410/T420/T510/T520 can all use the same keyboards, but from 3 manufacturers.
Hence frames from the same manufacturer will be interchangeable, regardless of language layout.
Look in e.g. T520 Manual under Parts list/Keyboard (download from the HMM link above).
There are 3 columns with keyboards there.
Left=Alps, middle=Chicony, right=NMB (best).
Check your own keyboard, it's most likely one of these: 45N2071, 45N2141 or 45N2211 (US English).
If you want just the frame, look for any language keyboard from the same column as yours.
Try e.g. eBay or our Marketplace.
You can then either transfer the required parts, or buy a whole new/used keyboard.
FYI: I have an as new, perfectly working 45N2211 (NMB) for sale,
as well as a 45N2141 (Chicony) with Arrow-up key faulty, otherwise OK.
PM me if interested (but shipping from Ireland to USA is not cheap).

[dr_st]

Nobody sells just that "frame" (for lack of a better word).

At least a couple of Aliexpress sellers seem to:
https://aliexpress.com/i/1005002660392530.html
https://aliexpress.com/i/32627451073.html

[kfzhu1229]

Left mouse button was removed when I took the photo but that was only for cleaning. After cleaning it's still little erratic and sometimes you have to press a little hard or more on one side of the button. I have no idea if the contact can be cleaned more assertively or do they at some point irreversibly wear out so I thought I should get a backup of this whole thing in case they finally wear out.

I took apart that thing as well, and found out that my cable is actually snapped outright due to an idiot not knowing how to remove the hard drive on the t520 and drilled holes thru it to destroy data instead.
in your case I would personally attempt to fix it instead. If you take the buttons out and deweld the plastic frame from the metal frame you can take out the membrane. youll see the mouse button as two big dots on each side of the membrane that will get smushed together when the button is pressed, and each dot is connected by a thin trace.
its possible your traces received some corrosion (usually exactly at the "neck" part that connects to the dot), usually identifiable by discolouration at that part. If that's the case I would use my conductive ink pen and drew silver traces on top of that and then cover it with clear coating and then the button will work like new.
it's also possible for the "simpler" outcome of just the dot part worn down a bit and then got easier oxidated. In that case you didn't even need to disassemble anything, just press down the button firmly two dozen times preferbly at each angle of the button, that friction can clear away the oxidation and the button will work much better for some time.
(The same things occur to keyboards sometimes too)