Re: 奴隷との生活 -Teaching Feeling-
There is a multitude of ways to translate cultural differences which are generally hard to translate. The most effective one is probably to change the attitude of the character in a way that allows the reader to still be able to tell what their relationship is.
1. You can change the structure of sentences to reflect what would otherwise be lost. Example (my japanese is balls so I will go the easy route and start with everything translated but the honorific):
Thanks for the help, onii-chan -> Pretty helpful, thanks big brother.
Thanks for the help, onii-sama -> Thank you for helping me, big brother.
This of course means that the general message needs to be altered (even if only slightly), which is what translators generally avoid to do with translations.
2. Another way was already mentioned by you, but is generally perceived as "cringeworthy", that is trying to translate the honorific no matter what. This will lead to something like this:
I helped onii-chan in the garden. -> I helped my cute big brother in the garden
I helped onii-sama in the garden. -> I helped my respectable big brother in the garden (this still sounds like ridiculing)
Since we are not used to specifically be reminded of how one character views another character, this just sounds awful (to me at least).
3. Finally, and this option seems to be pretty popular, is to keep the original in the sentence. Just to be sure, have an example:
Oniichan, if it fits, i sits -> Oniichan, if it fits, i sits
All three of those work and it is up to the translator to decide. Please dont choose option 2 though. Dont.