Ok, it works pretty much like it should with one exception. The language value was set to 'und' for all entries, causing them to be empty in edit node although they were visible while viewing. If updated and saved again a new row would appear in the database (so now I had one with a language value of 'und' and one with 'pl' in my case) which in turn caused views to display duplicated results. I removed the duplicates and updated all rows to 'pl' manually fixing the problem, now all nodes can be edited with no problem. I believe this should be fixed so the language column gets filled properly.