I, na lepo leu gesku ga bredi{,/}ice le fagro ga bilti cabro {/guo}, oe le mercejmeu ga fadgoi lesuo spali je le tribiafii, ice le merceafua ga fadgoi lesuo spali.
If the first comma is present, it terminates the na phrase, closing the lepo clause at the same time. I have presumed it was intended for the fire bit to belong to this clause. Omitting the comma ensures that the second part of the compound sentence belongs in the lepo, A guo is not essential but recommended as good practice, as a comma will close the extended na phrase, and force the closing of the lepo clause

Leu teidjo ga sacduo lepo gritu le lalkuo ge meala Xi,as po gritu, ice mi ze la BeibiDjein ji prase blekue go karsa je le fagro {/ga}tera genza radgoi le fagro.
Needs ga to parse.

I na lepo mio fadgoi lemio satci sitfa, mio renro ne hancai je {/leu}sliti sutherba, le fagro, e cutse li, Lui tu, lu.
An argument attached to a predicate with a je phrase must be an argument, so a descriptor, here the set operator leu must qualify the predicate sliti sutherba I have also changed some epa in the next sentence to efa (and then)

I mi kasgoi le satci sitfa je la BeibiDjein, ice Bai kasgoi lemi {sei/sitfa}.
A descriptor must modify a predicate. Hence this must be lemi sitfa, or lemi mesei.

I, mia nepo tu fui cirna la Xlang {/guo}, tu nina merji la bilti Xrmm'gyc
guo is essential here.

I miu papa setfa lemiu tenta go snire {/je}le vlako pe la Bragardea, e{/,}nafa bedgoi va, e kincle haispe le cimra natli.
To have the lake associated with snire, we need to link it with je. To avoid e nafa from becoming enafa, with a different meaning, a comma is necessary.