صَحِيحٌ فِي جُمْلَتِهِ
Sound in general or on the whole.
The qualifying phrase “fī jumlatihi” matters: it affirms the report's broad reliability without asserting that each word and figure is absolutely error-free. Removing it could, depending on context, suggest a stronger claim than the speaker is prepared to defend. This phrase defines the scope of the proposition.
Syntactically, “inna” introduces and reinforces the statement; “hādhā” is its subject, “al-taqrīra” specifies the demonstrative, and “ṣaḥīḥun” is the predicate. The qualifier is attached to that predicate. Emphasis and qualification are compatible: one strengthens an assertion, the other specifies exactly what is asserted.