The phrase "although it was largely" is correct and usable in written English.
It can be used to introduce a contrast or exception to a statement, often indicating that something was mostly true but not entirely so.
Example: "Although it was largely successful, the project faced several unexpected challenges."
Alternatives: "even though it was mostly" or "despite being largely".
The vastness of the landscape and its stark beauty were breathtaking, and although it was largely empty, there were pockets of life, usually around dry riverbeds, where there was just enough water beneath the ground to support life.
Fado became the national style of Portugal under the dictatorship that ended in 1974; although it was largely spurned during the 1970s, a younger generation embraced its musicality as the political taint receded.
Music critics Richie Unterberger and David Fricke have both noted that although it was largely overlooked by the public at the time of its release, the album's critical standing has improved over the years and today Younger Than Yesterday is considered one of The Byrds' best albums.
His appearance sparked an internet meme, although it was largely unrelated to his message of interfaith unity.
Although it was largely studied in the human or mouse, no report has provided functional evidence for it in the swine.
Victory in Scotland through Marco Ureña's slick finish recaptured the spirit of Italia 90, although it was largely absent against Tunisia in Nice despite some opportunities to equalise.
Traditional dress is occasionally seen in many regions, although it is largely reserved for official ceremonies and festivals.
Analysts at Jefferies said the FHFA bill was $1bn more than they had been expecting, although it is largely covered by existing provisions.
Although it is largely demonstrated that Autism Spectrum Disorders (ASDs) are characterized by executive dysfunctions, little is known about the fine-grained levels of this impairment.
The documentary does not apportion blame, although it is largely sympathetic to Nascimento and the police are shown to have been incompetent.
Ms. Disenhouse, who has a sense of humor, although it is largely subsumed by a desire to talk politics, will indulge you for a few minutes.
