Understanding adverbs are provided in this article. The words listed here are commonly found along with the verb understanding in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb UNDERSTANDING.
accurately, actually, apparently, clearly, completely
correctly, deeply, evidently, exactly, finally
fully, hardly, immediately, merely, necessarily
perfectly, precisely, properly, really, rightly
scarcely, simply, suddenly, thoroughly, truly
Hope this word list had the understanding adverb you were looking for. In addition to adverbs used with understanding, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.