To Josip.
That's fine. I don't see it quite long, but from first sight - it is almost perfect.
Couple of small things - anyway. Very long Rivers in Smolensk area.
Oka River - main feature of Russian plain must be - between Tula and Kaluga - not to west from Kaluga anyway.
Very big Briansk province. It mustn't have border with Tula at all. In real map we've got rather big Orel Province - between Tula, Kaluga, Kursk and Briansk provinces of reality. If we need this province - it is a big question (I would vote for it inclusion), but if we wouldn't - this land must be part of Kursk and Tula - due to their belonging to the same "Black-soiled" Russia Region. Then this quite fertile land must share rather high tax value - equal to Kursk or Tula, - not to swampy Briansk province, which must receive quite shitty numbers.
It means:
1) You must divide your Briansk province to half - anyway. Western part of it will be Briansk (swampy land with shitty numbers), eastern part - Orel province or parts of Kursk and Tula provinces.
2) Oka River must go to south cutting Tula from Kaluga (and Briansk - if you drop Orel) completely.
In case of Orel province inclusion - Oka River must cut Orel from Kaluga and Briansk as well.
It means - Moscow, Kaluga and Briansk on one bank of Oka River.
Ryazan, Tula and Orel (if included) on other bank of Oka River.
In start of Kursk province (just under Orel - if included, or under Tula if Orel isn't included) - Oka River disappears.
Velikie Luki of this map is actually part of modern Smolensk province and there isn't big rivers around, but there is a lot of swamps in area. I'm not sure if we need river between Smolensk and Luki, but this point is debatable.
Eastern hand of Don River of your map (which divide Tambov-Voronezh from Sarai-Saratow) is excessive - kill it.
We are missing Lipezk province of actual map, but its' inclusion is debatable, then its land would be divide between Tambov and Voronezh, but I'm not sure if Voronezh province would make common border with Ryazan province - any way. In actual map we've got ideal "diamond"-structure here - with
Ryazan as northern point of diamond, Voronezh - southern tip of structure and Lipezk and Tambom - making middle pair. Something like that:
Ryazan
Lipezk/Tambov
Voronezh.
I'm not sure if we need Lipezk province inclusion (but it would be rather nice idea), but idea of Ryazan and Voronezh as close neighbors - is quite revolting for my sense of history (Forest-filled Lipezk province by its climate and tax value is close cousin to Forest-partially filled Tambov province - not to steppe-like Voronezh anyway). It means - if we would drop Lipezk, then border between Tambow and Voronezh must be in latitudal direction, not in meridional. Do you see?
By the way - please, make Voronezh much bigger, by cutting a bit huge Sarai province. Hint: Voronezh and Saratow MUST be close neighbors.
In Russian chronicles Voronezh is used to have common name as "Southern shield" - i.e. rather long barrier in latitudal direction, which used to stop any Crimean tartar incursions. In this chart it isn't "shield", but rather - "spear" of some sort. Do you see?

By the way - in WWII times - ancient fortresses of "Voronezh province" became to be "natural" defense line, held by Soviet troops in German 1942 assault. Whole local front, which kept central Russia from possible German advance from South was named as "Voronezh' Front". Later - the same "Voronezh Front" name was applied to southern face of Soviet troops in Kursk battle - with the same idea - "Voronezh Front/Voronezh Fortress Line" is SOUTHERN line of defence for Russia.
Then Voronezh Province thing must be some sausage-like thing in latitudal direction, which must keeping all Tartars (from Sarai for example

, or Poles-Lithuanians (Ukrainians) from other side of Don River - to South from "Voronezh Front/Line of Fortresses".
This thing was southernmost line on the Earth, which Russians traditionally (till XVII century - anyway) considered to name as "Mother Russia".

All other lands - like Kharkov surrounding / Slobodshchina, or Lower Don/Kouban Valleys / Cossack lands, or lands in Lower Volga Valley was considered as "not quite Russian lands". For example - in WWII terms - "Voronezh Front" was southernmost group of Armies which received "Russian common name", but more southern Fronts start to receive names - like "Steppe Front", because - there wasn't another "Ancient Russian city" to south from Voronezh.
Do you see?
Sincerely yours, Bash