To me, I'm still not crystal clear on the timing and series of events..
IF the OP checked in online, printed his/her BP, but then lost it, that's easily rectified by getting a new one at the main check in counters- as you'd need one to pass thru Immigration control.
However, it *sounds* like perhaps the lost BP occurred after immigration, but before boarding.. If that's the case, then perhaps the gate staff considered the OP as a 'no-show' and his/her seat was reassigned as such..
However, post #2 makes it seem like a much more routine matter-- that being as noted in #3, as a simple case of airline reassigning a passengers seat (which is their sole right to do) after time of initial online assignment, but before boarding/departure.
So, I guess I'm not clear here on the issues of: 1) the lost BP and 2) last one to board... To me, these issues might have been a factor here, but again, I'd need to know better the timeline and sequence of events.
As to the staff understanding, speaking etc of English... Yes, there is a reasonable expectation of such as English is the accepted and official (operational) language of aviation on a global basis.. but, it's not always uniform and the level of proficiency isn't the same.. I don't think this is a mark of a failure per se, but is simply a reflection of where you are and who you're flying.
I cannot discount that there will always be, understandably so, a strong pre-disposition to the staff speaking of and understanding of what is the local language where the event takes place, or the language of the carrier.. That kind of is a case of "it is what it is"...
I'd expect that to a degree, if you were to look at the passenger profiles involved that they'd tend to reflect this reality-- a large percentage speaking the local language at the origin city, or the language of the destination country.
Lastly, to the issue of the cabin crew not helping.. To me, IF the issue was that they wouldn't help the OP *find room* for his/her bag, then I think that's a failure.... BUT.. IF the issue was the cabin staff wouldn't also help physically *move* the bag, THEN i think that's something different.
While the OP does use the words "help find", I leave open the possibility that this includes the moving, lifting etc, of bags or similar..
Some carriers do in fact either prohibit or strongly discourage crew from lifting bags due to possible injury risk.
Edited: 3:19 am, February 27, 2013