On faction tree (upgrades) if you click on some upgrade you can see all that is required for that upgrade. Each upgrade has a challenge. Some of challenges require users to do specific staff for example to spend energy on defense, and we are able to see how much energy anyone in faction spent on training defense - contributors. This data is updated at same time as player spend energy (or do other stuff based on challenge). That is what i asked for, to be able to get how much each player contributed to faction upgrade.
Usually this data is used to track activity of players, mainly for internal faction contests. For example player that spend most of energy in month of contest win price from faction. This i way how faction push players to be more active. Now we need to copy that data from web page to some text editor, to do a bit of manual work to prepare it for some spreadsheet where we keep it till some time pass and then we need to do all that manual work after some time so we can compare data. with this API we can do all of that with single call and store data, and with some simple loop compare progress of faction members.
Upper part was probably boring a bit, so i will now skip to some technical details. Maybe this will help you to easier find data what i ask for. When you click on some faction upgrade you have XHR call to
https://www.torn.com/factions.php with data {step: upgradeConfirm, type: 38, level: 1} where type is id of branch. as response you get object with all info about that particular branch and level. One of properties is called contributors and there is where you can find all data i ask for. This property is array of object that contain userid, challenge, and total for that challenge for that user. Data in API should be displayed for all challenges where every challenge is object/array of all users that contributed. users are objects pointed by userid where every user object contain total for that user and challenge and information is that user ex member. So at end result should be like example that is shown on first post.
Hope i given enough info.