In English, "west" would not be capitalized, as it is merely a direction, not the name of that region. I agree with another commenter's suggestion: "Bohemia is in the western part of Czechia." This is much more natural in English. Also natural would be "in western Czechia".
Definition of west (Entry 3 of 7)
1a : the general direction of sunset : the direction to the left of one facing north
b : the compass point directly opposite to east
a : regions or countries lying to the west of a specified or implied point of orientation
b : the noncommunist countries of Europe and America
Thanks for the dictionary reference. But... dictionary be damned, maybe there are some regional usage considerations.
Where I come from (US, East Coast/Mid-Atlantic region) you would rarely use, for example, "Philadelphia is in the South of Pennsylvania" or "Baltimore is the North of Maryland"; more likely would be "in southern Pennsylvania" and "in northern Maryland."
But if you come from the southern part of Philadelphia, you would probably use, "I come from South Philly," and if you were going off on a close-to-home beach vacation, you would probably use, "Where am I going? South Jersey, Atlantic City." If you were going farther afield for your fun in the sun, you might use, "Tomorrow I head out to South Florida, West Palm, for a week."
So...hmm. Go figure! :-)
I agree that the capitalization is just a grammar mistake but the sentence is fine for a main translation because it does a good job of finding a middle ground between the meaning in Czech and the meaning in English.
Very few English speakers(or even Czech) would use 'Czechia' and I think that is the part that sounds the weirdest. Obviously though the creators of the course made a very intentional choice to use 'Czechia'; so I don't think that's worth resisting as it's clearly their decided preference.
So... here's the thing -- you can rarely please all of the people all of the time. Some are unhappy with "Czechia" because it's new or weird or both. Others are unhappy with "the Czech Republic" because it's old or takes too long to type. So both appear throughout the course, and generally both are accepted in the English translations. So we hope at least some of the people are happy some of the time. :-)
I agree that "in western Czechia" sounds much more natural in English. Personally, I don't think "in the western part of Czechia" works as well, though there's nothing grammatically wrong with it.. Would "in western Czechia" require a different sentence in Czech?