The phrase "although it leaves" is correct and usable in written English.
It can be used to introduce a contrast or exception in a sentence, often followed by a clause that explains what is being left or the implications of that leaving.
Example: "The proposal is well-structured, although it leaves some important details unaddressed."
Alternatives: "even though it omits" or "despite leaving out".
Although it leaves you with a knot in your stomach, its power is undercut by its own head-banging obviousness.
Although it leaves much to be desired, this book has potential.
Waterboarding is an extreme form of torture which, although it leaves no physical marks, makes the victim believe he is about to drown.
VOIP changed that a bit, making it dead simple to grab the conversation as it passes through your phone client, although it leaves you chained to the desk.
Although it leaves the contents of your custom keys concealed behind icons with generic (but also customizable) names — such as 'Email', 'Name' and 'Message' — rather than sticking it right on the Qwerty.
Although it leaves on a profoundly inspirational act of quiet heroism and it feels complete.
Polish studio CD Projekt RED swept the awards boards last year with its role-playing game – although it left the Gaming BAFTAs of the spring empty handed, oddly, despite eight nominations – and with B&W is now calling time on the adventures of its titular monster slayer for hire, player-protagonist Geralt of Rivia.
Like Shout's gel, it got out nearly all the lipstick, although it left behind a lot of foundation.
"The taste was crisp and refreshing, although it left an aftertaste on the back of my throat.
It did offer some bright spots — such as progress on protecting the high seas from pollution, overfishing and acidification — although it left other dire threats unaddressed.
Although it left a lot of the hard work to be done in Paris and was relatively modest, last year's Lima climate summit did reach a deal.
