Can the plant names "Lilac" and "Licorice" be used as pen names? Would that be bad?

absolutely. Lilac has a flower language. If you use Lilac as a pen name, you can borrow things to recite poems. It is generally believed that cloves are pure.

Glycyrrhiza uralensis Fisch is a versatile Chinese medicine, because many Chinese medicines have bitter taste. Glycyrrhiza uralensis Fisch can neutralize the taste and promote the efficacy (Glycyrrhiza uralensis Fisch is the king of all kinds of medicines). Therefore, it is entirely possible to describe yourself by licorice.