In Chinese cuisine, are the black beans fermented in Black Bean sauce?
I'd say a resounding no.
ermm... or yes, depending on whether I'm answering your topic title, or the question in the question ;) 

You cannot use substitute beans, because the key ingredient for black bean sauce is fermented black beans. Everything else is an aromatic additive; easily substitutable depending on recipe &amp; intended result.

Leave out the Szechuan pepper, sure; more garlic, why not; different vinegar, yup: different soy, whichever you prefer...
leave out the black beans... it's no longer black bean sauce.

You can, if you're lucky, get fermented black beans in "the West".
I'd recommend a trip to eBay, Amazon, local Asian Supermarkets, etc, if you want to make your own.
Once you have those, recipes for home made black bean sauce are easily available on the web.

I'm not sure I'd tackle the fermentation myself - I'd leave that to the experts.

On a 'shopping' note - if you're in the UK look for makes like Lee Kum Kee which have a London distributor but are as 'authentically Chinese' as you can get. I have no idea whether they are comparatively good bad or indifferent to a Chinese person, but they at least have a definite origin on the labelling.
[no affiliation, just what I can find a lot of in my local Asda &amp; it tases alright to me.]
As a rule I avoid the 'foreign food for Brits' aisles* when shopping for foreign food - but your local market forces will dictate how much footage a supermarket will devote to 'real' vs 'friendly English substitutes' stock.

*Apologies if this may be considered 'inverse-racism' against my own culture - no prejudice intended except in flavour terms - but I prefer imported to 'made in Milton Keynes' when shopping for foods from other areas of the world.