When you need to indicate that something or someone is not up to the expected standard, "be found lacking" is a useful phrase. However, if you want to add some variety to your writing, there are many suitable synonyms. Depending on the context, you could use "fall short," "come up short," "be deficient," "be inadequate," "be wanting," "be insufficient," "be deficient," "be flawed," "be imperfect," "be incomplete," or "be subpar." Each of these alternatives gives a slightly different nuance and can be used in a range of situations, so experiment with them to find the perfect fit.