They've been doing that for a whole month and gained almost no territory as a result (while losing territory around Kharkiv and stalling in the south around Mykolaiv and Zaporizhzhia).
That might be an excuse for Russia's poor performance, but an excuse doesn't change the bleak outlook.
Time will tell regarding their central bank. The trade surplus is actually not a good sign for the Russian economy. It means that many Western-made products will become more expensive and/or inaccessible once the pre-existing stockpiles run out. Aside from unnecessary "luxury" like Iphones and BMWs, Russia will also struggle to maintain crucial parts of its infrastructure, e.g. it's pipelines, once attrition kicks in and they can't replace worn down high tech components.
The ruble is a zombie currency. The liquidity and activity on the ruble market has gone down so much that its exchange rate cannot be taken seriously anymore. And since the Russians continue to accept โฌ and $ for their oil and gas sales, there is no reason for anyone outside of Russia to buy rubles since there is virtually nothing of interest to buy with it. Also note that the current market environment is inflating the oil and gas prices. Once fears of an energy crunch are gone and/or production by OPEC, the U.S. (or even Iran/Venezuela) pick up, prices will come down again. In the intermediate future, Europe will move away from fossils, so good luck to the Russians when they try to ask the same prices that the Euros paid them from China or India...
That Russia's revenues from commodity sales have gone up in spite of lower sales volumes is pretty much the only bright spot for them right now, but like I just said, that's clearly not gonna last.
Saying "they lost the battle for Kyiv and Kharkiv, and there's a neverending stream of weapons toward their enemy while their reserves are dwindling, but they are firing hundreds of strikes on a daily basis and are on the offensive... how can they be losing war"
is about as short-sighted as someone in 1943 saying
"okay, the nazis lost the battle for Moscow and Stalingrad, and there's a neverending stream of weapons toward the Soviets while their reserves are dwindling, but they are launching an offensive and even won the 'Third Battle of Kharkov' [1]... they are on the offensive again and can still win this war".
[1]
https://en.wikipedia.org/wiki/Third_Battle_of_KharkovLol battle for Kiev. There was no battle for Kiev, that was a scare tactic to get them to throw out their gov't. Once it didn't work they pulled back their troops. You think 30k troops was enough to take a city of 3 million?