I haven't used Reader for many years -and versions. I do remember, however, that in the Preferences of older versions, you could choose between English and whatever (Spanish, for example) for the appliction language.
You'll have to uninstall the spanish reader if you want to install english reader.
Or if you have MUI reader installed on your system and have installed all of its supported language resources, then you can change the appplication language in Preferences-->International.
It is true that if you want to have the English-only version of Reader, you would have to first uninstall the Spanish version and then install the English one. However, what I remember from older versions of Reader is that, in my localized Spanish version, I could change the application language exclusively from Spanish to English and viceversa. I don't know if this functionallity is still available in the present version of Reader but, if it is, it would be the answer to the specific question of the original poster.
The functionality to be able to change application language is still present in reader, as I have previously mentioned, in Preferences-->International.
Although in order to do so, one needs to have installed that specific language component.
This is common with MUI reader where one can specify multiple language components during installation and switch between them anytime.
No, I am talking ab
out the plain Reader in Spanish
one downloaded automatically without any special specifications. Theoretically, it should have been a Spanish only version, but one could change the application language betweeen Spanish and English any time, and any number of times, in Preferences -> International. I understand the same was true of other localized versions of Reader: one could switch between that language and English to one's heart's content.
Extra linefeeds kindly provided by the software.