You can only translate "Wha-" so many times before you gotta change it up a little.
For professional translations (at least, for IT manuals, dunno about official regulations for manga) there are certain specific requirements to make sure non-native speakers of the target language can properly understand the translation. So random silliness irks me, because I've done the same in the past and I got a thorough talking-to for it.
Manga has no official regulations for translation - different translators and different groups will all have their own views on how to translate - how literal to be, what words should NOT be translated, how to make changes or not to reflect cultural differences or practices, etc etc.
For example I like honorifics left in if appropriate - they give extra detail and subtlety, especially where they change- that is lost if they are not used - and the alternatives often sound stupid (i.e big sis for onee-sama) but some translators will never include them. I hate when something is translated into an American equivalent, like yen to dollars, but some do that - or a Japanese cultural things name is replaced with a descriptor - like squid balls instead of takoyaki - but you also see that sometimes too.
The goal in translating manga / fiction is to convey the same or very similar meaning / feeling - and sometimes that means making changes too - I've heard it said trying to be too literal is a beginners mistake.
Translating a manual is very different - the only things that matter there I'd imagine are accuracy and clarity in conveying the information.