Starting translation isn't possible - both IE10 and IE11
Starting translation isn't possible on both Internet Explorer 10 and IE11, not by using "New translation" dialog nor by clicking on item in 'In progress' list. "New translation" dialog is working up until "Start translation" button is clicked. Clicking item on In progress list (assuming you have started translation in some other browser) starts opening translation view, but JS breaks and nothing happens afterwards. This is image from period before T160918 was implemented, but the end result is pretty much the same, so it's probably broken since T166854.
Same JS error prevents both ways of starting translation: jQuery.Deferred Exception: Object doesn't support property or method 'values' (TypeError) in mw.cx.getDefaultTargetNamespace. The method used isn't supported in any of Internet Explorer versions.
Suggestions not working on IE10
When suggestions start loading, featured articles are displayed and loading indicator shown, while rest of suggestions are loaded. When loading of other suggestions is done, while processing items, JS error happens and "Unable to show suggestions" panel is displayed. JS error is jQuery.Deferred Exception: Unable to get property 'listid' of undefined or null (ReferenceTypeError) in CXSuggestionList.prototype.insertSuggestionList while sorting items by ID. This happens because dataset isn't available before IE11.