So Russia ends up having much more Poles and annexes all Galicia and not just Eastern one. Episode with POW seems rather typical: this would not be the first case when enthusiasm and expectations of the foreign help went ahead of the realistic assessment of the situation (by that time worked only during the war of the 4th coalition with Nappy being around but failed in all other cases). So the hopes for independent Poland are dead and Nicholas has an excuse for not rushing with autonomy. Taking into an account that Russia is in possession of Turkish Armenia (and France and Britain want much bigger and profitable parts of the Ottoman Empire) the only really controversial part is fate of the Straits.
Actually, your scenario of the improving Russian-German relations may force France to adopt a more conciliatory attitude toward Russia because otherwise the French gains may start looking insecure.
And this will not become a long ongoing very bloody struggle for Russia, especially in a period of great economic and political struggle that's the aftermath of the greatest massacre know to man, sure not really. Dmowsky support and legitimacy will remain stable if he deliver something with his policy, otherwise soon or sooner he will become just a laughthinstock without any credibility and unfortunely statistically speaking Nicky and co. capacity to take the right decision are very low, not considering that while we don't know much about the type of fascism that will take helm of Russia in the future...well at least in OTL in general this type of regime don't have that great record regarding minority rights.
An improved Russian-German relation can also bring the British to support much much more France at Versailles or being much more 'strict' regarding reparations; not considering that if Petrograd become much more cozy with Berlin well support for this https://en.wikipedia.org/wiki/Rhenish_Republic and the general occupation of the Rhur will be increased.
Hell, with this type of policy Italy unlike OTL will not find much opposition in France and UK regarding his expansion of influence in the balkans, especially if against Serbia that will be perceived as a russian ally and in this scenario the russian delegation can huffin and puffin but there is little that they can do except protest as they have spent already a lot of political capital.
Basically this is not the end of WWII with Stalinist Russia in firm control of half of the continent, lot of legitimancy and even some level of popular support in the occupied zone; no this is a Tsarist Russia with a problematic economy, political troubles looming, massive loss in term of blood and treasure, ongoing terrorist act in the polish land that will probably become only worse if a political solution is not found, a leadership that's can be described as subpar if one want to be kind but lucky as she had just survived a potential revolution. In poor words, the entire russian infrastructure is shacky and can't obtain all what she want or project power everywhere while the rest of the entente accept the fait accomplit, plus Sazonov idea of take trade agreements instead of money unlike the rest of the entente will probably be beneficial like a bullet in your reproductive organ. Sure it's a smart idea but the german leaderships that's more or less like OTL will go for the hyperinflation plan and we have seen what will produce, so become more tyed to the german economy will be hardly a good thing, plus there will be the occupation of the Rhur and ITTL the plan of separate it from Germany will have probably much more support.
Snip
Well, seriously nobody can really consider Nicky, his wife and the cronies that generally obtain their favor competent on their job...even before the war, there was a reason that in OTL Russia fall on revolution and civil war; as i said, they made look the italian political class of the time competent and this is an achievement. Expecting this type of men to create a steady and competent postwar leaderships for a nation that had suffered so much loss in human and material terms and with all the political and social consequences it's almost ASB.
Sure even the rest of the entente was dependent of american loan, still the russian situation is worse, not only she is indebted with the British and the French due to the war cost that has been financed and the prewar loan, but she also need a lot of money to rebuild his economy and infrastructure, just in OTL Russia had more than 2200000 dead in WWI, before the civil war and almost 4 million of wounded and ITTL the numbers and destruction will be higher due to the prolonged fight and the German 'hail mary' offensive). Sure for now the civil war seem not in program, still things will not going back as before after such massacre and chaos is unavoidable especially with the current leadership