Как по Английски будет малоизученный

verb

Study (a role or actor) as an understudy.

Примеры использования:

He had to understudy prospero

noun

(in the theatre) a person who learns another's role in order to be able to act at short notice in their absence.

Примеры использования:

He has played as understudy to celtic's usual goalkeeper

adjective

An understudied subject has not been studied as much as it should be or as much as you would expect

Примеры использования:

The terrapin is a surprisingly understudied species., heart disease in women has been understudied …