Ah yes, separated by a common language.
Max.

So I assume that a "bloomer" is a "screwup" or "mistake"? Or what is it?

 

So I assume that a "bloomer" is a "screwup" or "mistake"? Or what is it?

Yes, according to google:

bloomer2
noun
BRITISH informal dated
noun: bloomer; plural noun: bloomers

1. a serious or stupid mistake.
   "he never committed a bloomer"

 

Yes, according to google:

bloomer2
noun
BRITISH informal dated
noun: bloomer; plural noun: bloomers

1. a serious or stupid mistake.
   "he never committed a bloomer"

In that case, "Bloomer" seems a bit severe. I would call it a misunderstanding.

 

In that case, "Bloomer" seems a bit severe. I would call it a misunderstanding.

Or a blooper??