Have yeasts that are used for making bread,  been used for making cheese, beers/ethanol and other products, and viceversa;  or do not always work well outside the 'customary/intended'  application?

Are several different yeasts ever used simoultaneously combined at a variety of proportions to produce something ?

I did see a YT of this couple who were making Kefir and bread using the same strain of yeast.  While later I couldn't find the same video, but I do recall it.

18 minutes ago, Externet said:

Have yeasts that are used for making bread,  been used for making cheese, beers/ethanol and other products, and viceversa;  or do not always work well outside the 'customary/intended'  application?

Are several different yeasts ever used simoultaneously combined at a variety of proportions to produce something ?

There are quite a few examples. Often they fall under the general term of mixed cultures or mixed fermentations. A sourdough is such an example as it generally involves entierely different species (typically yeast and lactic acid bacteria). Some craft breweries use mixed yeast strains to obtain differences in taste as another example. Here it is the same species, but using genetic variations to expand the metabolic profile. However, in large industrial processes pure cultures are preferred, if possible as they are  allow for more controlled and reproducible results.