Hi,
I am the one originally tried to identify this citrus.
I find this research and debate very interesting, thanks everyone. I am following it but cannot add too much valuable information as I dont know much about citrus taxonomy.
Just some observations regarding the names “jara lebu”, “shatkora” and its variants... it seems to me that they are broader names and often used interchangeably.
We have two Bangladeshi shops selling it nearby and in one of them they call it “jara lebu” and in the other one they call it “shatkora”. At same time I found in freezer a different citrus, named shatkora too, i will attach pictures of that fruit. I understand this rounded, smooth skinned fruit is used as cooking vegetable in currys.