Your problem comes from the word فَلَك, from it comes the word orbit, but does it really mean orbit?
I'll quote It's meaning from the Major Arabic dictionary Lisan Al-Arab (completed in 1290 - 688 Hijri):
الفَلَك مَدارُ النجوم والجمع أَفْلاك والفَلَكُ واحد أَفْلاك النجوم [...] وفَلَكُ كل شيء مُسْتداره ومُعْظمه.
The فَلَك is the orbit of stars, its plural is أفْلاك, and فَلَك is the singular, i.e, one orbit of the orbits of stars [...] and the فَلَك of everything is the rounding of it or the majority of it.
مدار is the "place form" of the verb دار, which means orbit (the verb), so مدار means orbit (the noun).
So obviously yes, Qur'an refers specifically to the orbit, i.e, the round way/road which sun and moon move (float) in.