My airline does not normally fly to Russia.
But we sometimes do charter flights - i.e. football teams.
xxx
In Russia we fly QFE and metric, we talk QFE and metric to ATC.
QFE are given in mB by ATC, but can be also given in mm Hg (760mm = STD).
Two of our 747-200s used for charters have a metric altimeter installed.
These altimeters have 2 Kollsman windows - hPa and mm Hg.
We use QNH/feet of the corrected altimeters to crosscheck the QFE.
With checklists/SOPs - we read back ALL DIGITS and read back the UNIT.
xxx
I trained the 747 TransAero (Russia) crews 4 years ago.
And delivered their planes along with their crews.
Obviously, they use QFE/metric.
Had to stress the use of QNH or QFE in the training in simulators.
xxx
My opinion is that it is dangerous to "convert" QFE/QNH and feet/metric.
You are likely to make a mistake one day, or misread a table.
So learn their procedures, and get properly qualified to do so.
xxx
As usual, some will do completely different procedures.
Glad I retire in 45 days... No QFE/QNH at the beach in Brazil...
Units there, are "um Chopp de Brahma"...!
Happy contrails