Can one say "should this matter" in the sense of "in case this matters"? For example in this sentence:
The company XYZ is registered in Portugal, should this matter.
It is a correct usage. It means "I think it's unlikely, but it's possible that it may matter to you where the company is registered.
The construction is used when we want to suggest a slight possibility of something happening or when we are making suggestions or giving advice.
Examples:
Should you fail the exam, you can always retake it next year.
Should you have any problems, feel free to contact me.
Yes. An inversion such as "should this matter" is a literary construction which is precisely equivalent to "if this should matter".