Is it correct to describe the Quran as "capital" in order to encourage its review, even though this term may be associated with what is permissible and impermissible in worldly transactions?

There is no harm in using the phrase "capital" to express the importance of reviewing the memorization of the Quran, as it signifies something of great importance to a person, such as time, age, religion, or obligatory duties. This phrase has been used in the words of sages and scholars, such as Ibn Ashir, who considered the preservation of obligatory duties to be akin to capital.