Learnt adverbs are provided in this article. The words listed here are commonly found along with the verb learnt in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb LEARNT.
certainly, early, easily
gradually, lately, previously
probably, quickly, really
recently, subsequently, thoroughly
Hope this word list had the learnt adverb you were looking for. In addition to adverbs used with learnt, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.