I want to avoid using commas, but number 6 feels unnatural without one.

Literal

Comma [object-を] not-put [purpose-ように] want-do [explanatory-んだけど], 6 [topic-は] comma [subject-が] not-exist-[when-と] unnatural feeling [subject-が] do.

カンマ 'comma' — a loanword used in both Japanese and English grammar contexts. ~気がします 'I have a feeling that' expresses subjective impression. The sentence is about punctuation conventions — a meta-linguistic writing concern.