The phrase "although there were numerous" is correct and usable in written English.
It can be used to introduce a contrast or exception in a statement, often followed by a clause that presents a different perspective or outcome.
Example: "Although there were numerous challenges faced by the team, they managed to complete the project ahead of schedule."
Alternatives: "despite the many" or "even though there were several".
Although there were numerous protests during the World Cup, they were small and did not detract from a tournament that, by and large, was carried off with few glitches.
The latter theory was almost universally adopted until the middle of the sixteenth century, although there were numerous variants.
Although there were numerous P. elongatus detections in young forests, higher proportions of these individuals were juveniles and sub-adults when compared to populations in late-seral forests.
Although there were numerous twin and family studies similar in design and outcomes, we were unable to pool heritability estimates for any outcomes for two main reasons.
Although there were numerous investigations into the supposed causes of the Flash Crash, including by Congress, the Securities and Exchange Commission and the Commodities Futures Trading Commission, none have been very convincing.
Nevertheless, we found no colonies greater than 160 cm at Kiritimati, although there were numerous smaller colonies apparently resulting from the partial mortality of previously larger diseased or degenerating colonies.
Although there are numerous opposition parties, they are barely represented in parliament.
Although there are numerous osprey in nearby Hempstead Harbor, there are no eagle nesting places on Long Island, nor is Glen Cove on an eagle migration path.
Although there are numerous legitimate reasons to have a Swiss bank account, in some cases individuals took advantage of bank secrecy to hold undeclared accounts.
Yet although there are numerous wineries around the country, in the modern era Greek wine has never achieved the place it deserves on the international market.
Although there are numerous innovative projects seeking to improve the sustainability of Australia's energy sector, one of the main barriers to making them happen is – as with most things – money.
