I do not know of any reason it would be wrong to use the articles in bold. I would use them myself (N. Am. English native speaker).
But it's not just my opinion: this is the practice at The New York Times (search article cited for "the Clarett Group", a defunct developer for which the article "the" was never part of its name, as opposed to other companies like The Trump Organization, where "the" is part of the name). Other sources writing about the same developer also follow this practice (notice that the name in bold does not include the article "the").
This is also perfectly in line with usual practice when referring to other names made up of adjectives plus common nouns ("the New York Yankees", "the Catholic Church", "the Department of Homeland Security", etc).
A better question is, when would you not use "the"? The only time it would be obviously inappropriate is if you were referring to company names that can only be read as proper nouns:
Part of Microsoft and the developer of the Zerkalnaya mine, JetBlue Airlines has been unable to pay interest...
Here it would be obviously incorrect to say "the Microsoft" or "the JetBlue Airlines".
This is a rather complicated issue. Your examples are from M.Swan's PEU, aren't they? But look how Geoffrey Leech and Jan Svartvik in A Communicative Grammar of English treat it:
The also has a generic use, referring to what is general or typical for a whole class of objects.This is found with count nouns:
The tiger is one of the big cats; it is rivalled only by the lion in strength and ferocity. [1]
Here the tiger indicates tigers in general, not one individual. Thus [1] expresses essentially the same meaning as [2] and [3]:
Tigers have no mane. [2]
A tiger has no mane. [3]
[2] is the generic use of the indefinite plural form; [3] is the generic use of the indefinite singular.
When we are dealing with a whole class of objects as here, the differences between definite and indefinite, singular and plural, tend to lose their importance. But there is a slight difference in the fact that the tiger (generic) refers to the species as a whole, while a tiger (generic) refers to any member of the species. We can say:
The tiger is in danger of becoming extinct.
Tigers are in danger of becoming extinct.
BUT NOT : *A tiger is in danger of becoming extinct.
I'm not a native speaker, so it's rather puzzling to me too.
Best Answer
Proper nouns have a "built-in" determiner and don't need articles.
However, you are using both names as adjectives to describe the noun region, so you still need the determiner.
If you were using the words as nouns then no determiner needed since they'd be proper in English too.