Lindeman's Beer has a hechsher from the Triangle K. This hechsher is recommended (by many kosher agencies) only for certain products. Is there another organization that has also verified the koshrus of this product?
Do you mean their fruit or flavored beers? If you're just talking about a plain-old Belgian beer containing nothing other than grain, hops, and yeast, it's basically a non-issue, kashrus-wise.
All standard unflavored beers with no additives are acceptable, even without Kosher certification. This applies to both American and imported beers, light, dark and non-alcoholic beers. Flavored beer, including those flavored with spices, botanicals, or fruits, require hashgachah.
(Though I believe the Star-K prefers to give a blank check only to domestic unflavored beers, just to play it extra-safe.)