"Waliposoma walijua Kiswahili"

Translation: Once they studied, they knew Swahili

[TessEwing1]

Why wouldn't "When they had studied..." work here?

[Daleswords]

TessEwing1 "When they had studied" and "Once they had studied" are completely interchangeable english phrases. "Once they studied" is incorrect grammar since in this case 'Once' separates two periods of time.

giraffe__ Please note that "li" is consistently translated as "had" in the kwisha/-sha- section as in "had already". So, if it is incorrect, it is, at least, consistently incorrect in DL.

[giraffe__]

the "li" in waliposoma indicates regular past tense, not past perfect "had" tense

[Francis795959]

.... but where does that 'once' come from ....

[MorwennaGr1]

But in English 'When they had studied' indicates simple past. You can't say 'when they had had studied'

[Graham932070]

Daleswords is correct. Throughout this segment "li" is consistently translated as "had", e.g. alipofanya kazi (when he had worked) against alimefanya kazi (he has worked".

[Joanne325766]

You would not say alimefanya kazi, it would be amefanya kazi (he has worked)