Few observations:
1. QFE/QNH is one of the areas for concern.
2. Polish Air Force TU154 pilots have little chance to get more hours other than on "live" VIP flights. Some training for sure, but you can't expect they will do a few thousands of hours on training flights. None of East European airlines operating TU154 for quite some time now, so it is next to impossible to arrange pilots to fly commercially to get more experience. However, I would say crew experience was more or less in line with other military crews flying heavy transport like C130/C17/C5/IL76/AN124.
3. Other areas to look at are rules and procedures. Polish Air Force aircraft flying into Russian military airfield controlled by military ATC. I'm pretty sure that rules were bended and corners were cut to make it happen in a first place. I don't belive that PAF crew went though the approapriate training at Russian Air Force and completed some tests/exams to become officially qualified to fly into russian military airfields. Most probably they received a short briefing, not more, and got some information from older comrades who were flying in Soviet times. Quite possibly a mismatch in understanding of procedures between crew & ATC played its role, add a less-than-fluent language knowledge.