Salamun Alaikum Chadiga,
I think this is simply a case where the translator (in this case, our late brother Asad) is capturing the essence of the message rather than giving a literal translation.
Whichever way you translate the verse, the command is that we should be conscious of our presentation before we worship our Lord during prayer whether this is in a mosque, at home or anywhere else. A ‘masjid’ literally translates as a place where one does 'sujud'. So this can be any place where the practice of 'sujud' takes place. Yes, there are dedicated places of worship, but this may not always be the case.
So what brother Asad seems to be capturing is the main message, which is to be conscious of our personal appearance / adornment, presentation before we pray whether this is in a dedicated mosque / at home, or somewhere else.
So rather than appear exclusive, he has translated it in a way to appear inclusive capturing the main message of the verse. This is also indicated by the Arabic 'inda kulli masjidin' (at every masjid) which means 'at all places of prayer' (in other words, whenever we do an act of prayer).
I hope that helps, God willing.
Joseph.