Ethnic Germans in Russian service in Poland

According to Polish and Russian Wikipedia, between 1909 and 1912 gen. Brusilov was a commander of the 14th Army Corp, which was quartered in Lublin. Later in 1912-1913 he became a vice-commander of Warsaw Military District, under Georgi Skalon. Skalon himself was a commander between 1905 and 1914. This way when Brusilov joined him, Skalon already had 7 years to chose the people he wants to cooperate with. Especially that in 1905 Skalon introduced martial law in order to deal with Revolution, which also took place in Kingdom of Poland (read about it here).

Note also that Skalon was not even of German origins. His family came to Estonia (where he was born in Tallinn) as huquenots from Sweden. But they weren't even Swedish - according to one of Polish language historical boards, his ancestor George Scalon came to Sweden from France in 1685, after the Edict of Nantes was withdrawn by Louis XIV.

Now we need to look into an additional source material. What I've found is that Brusilov was not the only one, who noted such coincidence. Roman Dmowski, one of the most important Polish politics of those times, wrote in 1925 in his book "Polityka polska i odbudowanie państwa":

Historyczny rok 1914 zastał w Warszawie najwyższe urzędy obsadzone w sposób następujący: generał-gubernator, z władzą cywilną i wojskową von Skalon [z rodziny hugenotów osiadłych w Szwecji, potem w Estonii, luteranin, mówiący w rodzinie po niemiecku]; jego pomocnicy: do spraw administracyjnych -Essen, do spraw policyjnych Uthof, do spraw wojskowych Rausch von Traubenberg; gubernator warszawski baron von Korff; jego pomocnik Gresser; prokurator Izby sądowej - Herschelmann, jego pomocnik Hesse; dyrektor filii Banku Państwa - baron von Teisenhausen; szef policji - Meyer, szef zarządu miejskiego [mianowany przez rząd prezydent miasta] - Muller. Tylko kurator okręgu naukowego nosił rosyjskie nazwisko.

Google provides the following translation:

Historic 1914 found the highest offices in Warsaw planted as follows: Governor-General, the civil and military authority from Skalon [Huguenot family settled in Sweden, then in Estonia, Lutheran, telling the family in German], his helpers: for the administrative-Essen, for the police Uthof to military affairs Traubenberg von Rausch, the governor of the Warsaw Baron von Korff, his assistant Gresser, the prosecutor Chamber of court - Herschelmann, his assistant Hesse, director of the branch of the State Bank - Baron von Teisenhausen, the chief of police - Meyer head of the municipal administration [government-appointed mayor] - Muller. Only the district superintendent wore a Russian scientific name.

We find here some of the same surnames, while with more details who was responsible for what. What's very important is that both Brusilov and Dmowski were nationalists, who were strongly against Germans. Unfortunately I don't know if it's possible that Dmowski read Brusilov's memoir and was inspired by him to write it.

From the words of Dmowski we can clearly see that many of persons mentioned by Brusilov were nominated by each other, as they surely wanted to cooperate with "their own" people. F.e. Essen, Uthof and Trauebenberg are mentioned as assistants of Skalon, Hesse was nominated by Herschelmann and Gresser by baron von Korff's, whose cousin was Skalon's wife etc.

I also see there the surname of president of Warsaw, Aleksander Miller, who's also referred as Müller by Wikipedia, but who was born in Sankt-Petersburg. The list of town's presidents shows that usually presidents were Polish. There were two presidents of half-French or half-German origins, but it was 60 years later. There's also one Russian.

Also governors of Warsaw Military District before Skalon weren't of German origin.

Military administration outside of Warsaw

With military administration, mentioned in the original question, it's a bit different. Here are some military high officers with which Brusilov could cooperate, except for Skalon's administration.

What about other high officers in the same rank as Brusilov? The commander of the neighboring 15th Army Corp was an Orthodox born in Tallin.

I would also take into account the leaders of units under Brusilov's command, as those officers with which he had the contact most often:

• Recent commander of the 1st Shooters (?) Brigade was educated in Moscow (I have no idea where he was born and no clue how to translate "brygada strzelców").
• Unfortunately I've got no sources for the commanders of 2nd Shooters (?) Brigade
• Recent commander of the 13th Cavalry Division was Georgian prince.
• Recent commander of the 14th Cavalry Division was Orthodox noble educated at elite Russian Page Corps.
• Recent commander of the 18th Infantry Division was a noble educated in Kiev.

Taking that into account, I find no reason to mention here military men among civilians.