So, the “_index.md” bundles can have images etc. as resources (and not other pages), but only on the same folder level. So if you treat the home page a litle bit special:
_index.md
_index.de.md
logo.png
bio/index.md
bio/index.de.md
bio/images
It will work. @kaushalmodi is the bundle expert, and can chime in if I got it totally wrong … (I implemented it).