The beta version went live this afternoon.
http://www.kiva.org/portfolio/estimated-repayments If you like it, bookmark it, since there are no links to it on the site at this time. (This also means sector is now on the lend tab and the borrower page, thanks Cailin!)
Richard, it sounds like what you're describing would be best implemented as a separate tally. The scheduled repayments is looking into the future, and you'd like to have similar functionality but looking into the past where things like currency exchange loss, delinquency/default amounts, pre-payments, etc are known. In this other feature, let's call it "Past Repayments" for now, it would show past month summaries and stop on the current month. I think combining them would mean that there'd be a lot of empty columns once you pass the current month and rather than trying to have one screen solve both sides, just have two separate screens so that each one can specialize in what it's looking at.
I definitely agree that having the scheduled v. actual amounts, outstanding, +/- difference, defaulted, and currency loss by month's in the past would be very beneficial... and that is already part of the plan... but those numbers make sense for the past... not future... other than to indicate how much ahead or behind your loans are overall (just one number listed, not done by month).
I tagged the feature as "BETA" though if I were to put a version number on it, I'd call it 0.1 -- It has to start somewhere. To David's point about having beta releases as standard practice, when it's a new feature/page, with a separate URL, it's easy to just not link to it or have user groups where only those in the group can access that page. But if it's reworking existing pages, having the site operate with both sets of code for the testers/non-testers becomes problematic for a variety of reasons.
What is the intent of the right side of the screen?
A recurring request from many lenders is for better ways to go inspect what's going on with various loans that are paying back. I agree that when you have a lot of paying back loans, it's a lot to look at. Not everyone lends like that (the vast majority do not), so if you don't find this useful, don't use it. There are many users who have a relatively low number of loans and want to check up on the borrowers they'd spent hours selecting. For me, I have a loan coming due this month that was the largest amount I'd ever lent to a single borrower (now that my teams are not penalized for it anymore), and it only has one repayment. So, having that borrower sorted right at the top keeps my eye on it.
I'm looking at replacing the grid on the right with one that is sortable/groupable (with summary numbers for the group) and filterable at the client-side with AJAX fetching for more data... probably add some more columns as well. So you could choose to only show the delinquent loans, or only the Agriculture loans. Potentially have it switch modes if you have more than a certain number of paying back loans, only give summary results broken out by various methods and in greater detail than what shows down the left side, with the ability to drill into the data more. The reason the interface is so basic is because I don't refine it until I've decided that's how it will stay and I like to be able to play with it to get more ideas. Concerns over date formatting don't come into play until I've decided that I'm keeping that table at all -- I'm thinking that I'd like to make the bar charts vertical and clickable and replace the left-hand table. Not sure yet.
In this example, can you give us an estimate about what it would take, both technically and administratively, for Kiva to implement a basic yet complete Loan Repayments History summary for each Lender?
If you'd like to apply for a position to manage future features, timelines, and development priorities based on estimated labor costs, Kiva is hiring a product manager.
http://www.kiva.org/jobs/job-product-manager-consumer-apps 
One thing that I find lacking is I still need to do manual math to find out how much total shortfall a delinquency represents
Agreed! I'm already looking at getting that into the appropriate places.
Paul