[kurlannaiskos]

Originally Posted by kolya1

There may some confusions in Russian documents because many A-20s were modified in soviet service, notably to reinstall a glazed navigator position in versions which didn't have one (using among others glass panels from Il-4s).

there is confusion , but it is not in soviet records.
the confusion comes from us in the west trying to put things into little boxes where they do not belong.
to the Soviets it is simply a 'Boston' not a '-this' or '-that' they really did not care for such record-keeping problems.
the Soviets did make many modifications to the Boston,everything from cold-weather improvements to armament upgrades to bomb racks and torpedo bridges for external ordnance.
your use of the term 're-install' is somewhat misleading as the 'G" model was built for the attack role , not for bombing.
instead the metal panels designed for maintenance access to the four .50 guns were removed and replaced with clear ones, and a navigators station was built in the space where the guns were.
some aircraft were modified with this navigator's station in the rear, some feature glass in the front and rear!

Originally Posted by kolya1

Others were provided with a soviet-made radar,...

it may have been made in the USSR , but it was a copy of a captured German unit.

Originally Posted by kolya1

P.S. : I think that on this web page, the second A-20 photograph depicts such a modified airplane.

Yes , indeed it does !
this plane was an A-20-G35-DO that was converted in the USSR for the anti-shipping role as it was operated by one of the MTAP's (Mine and Torpedo Aviation Regiment)
in the US this aircraft is designated A-20G-36-DO to indicate a Soviet modification to a G-35
this particular plane 'Tallinsky AP' is translated as 'Tallin Air Regiment' and was applied as an honorific.