I have kontakt 5.4.3 & 5.5.2 . work side by side.
and I have tens of kontakt libraries.

I know that I can go to each library website and see what kontakt version require to work with the right library.
but I am just wondering, if I can find a Reference for all kontakt libraries and what version they require to work ?

 

You can delete your 5.4.3. Every libraries working with 5.4.3 are working with 5.5.2.

 

Not sure he can i.e if he installed side by side he simply extracted the .exe & .dll from 5.5.2 therefore he needs the installation files from 5.4.3 to make side by side 5.5.2 work.
If he uninstalls 5.4.3 locations such as C:\Program Files\Common Files\Native Instruments\Kontakt 5 will be deleted therefore left with only .dll & exe from 5.5.2 may not work. Could be wrong tho

 

To answer the question the OP there is NO universal Kontakt Register AFASIK.

Reason Each developer encodes which whichever version they see fit.

For example, some dev's still even encode in 4.2.4 for example so that users with Kontakt 4 can also use the library i.e Backwards Compatability i.e a patch encoded in 5.4.3 will not work in any version lower than 5.4.3.
U also have the added problem that some of these libraries have been batch re-saved etc therefore you cannot always for certain know the Authentiticiy of the patch.
A user may upload a library that was encoded in 5.4.1 and resaved in 5.5.2 and because of backwards compatibitlity issues the patch will NOT work in 5.4.1 as it should.

Therefore use "scene" releases in general.

It is easy enough to go to a website & check the minimum requirements

Anyway if you have 5.5.2 loaded side by side you don't need to check. Simply do not re-save any patches with 5.5.2 or they will NOT work in 5.4.3.

ALL your libraries will work in 5.5.2 but not all will work in 5.4.3.

However with a side by side installation if you un-install 5.4.3 then 5.5.2 WILL NOT work as it should.

The only way around this would be to save ALL the relevant data needed in the correct locations & re-insert after you delete 5.4.3

Best idea leave well alone and any patch you save with 5.5.2 will subsequently NOT work in 5.4.3