I have to second what hv already said, this description

> The overall record is enclosed with brackets and is composed of KEY, VALUE pairs.

doesn't fit the demonstrated sample. There are more types like LIST and QUOTED-STRINGS and especially the first "KEY" (?) sys ecm cloud-provider /Common/aws-ec2 is very confusing.

You should better provide an SSCCE (update: especially the expected output)

> Any advice on the best way to approach it would be greatly appreciated!

Regarding recursive structures

> the VALUE, which can be simple text or another bracketed sub-record.

you might want to have a look at

• perlre#(?PARNO)-(?-PARNO)-(?+PARNO)-(?R)-(?0)
• perlretut#Recursive-patterns
• Parse::RecDescent

EDIT

FWIW: I think after tr/-/_/ I could parse this as a non-strict Perl DSL, just by predefining the key-words as subs. But w/o better specification (whats a keyword, what a bareword/string) of the desired outcome, there is no point in attempting it.