Functioning adverbs are provided in this article. The words listed here are commonly found along with the verb functioning in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb FUNCTIONING.
actively, actually, adequately, barely
correctly, currently, effectively, efficiently
fully, highly, independently, normally
optimally, perfectly, poorly, primarily
properly, really, smoothly, successfully
Hope this word list had the functioning adverb you were looking for. In addition to adverbs used with functioning, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.