A fractional or interim Chief Architect is useful when an organisation needs senior architectural judgement but does not yet need, cannot recruit, or should not permanently staff a full-time role. Typical triggers are a major transformation, weak architecture governance, a complex vendor landscape, portfolio simplification or a period between permanent leaders.
Good fit
The role works best when there are real decisions to make, internal teams who can execute, and executive sponsorship for cross-functional architecture.
Poor fit
It is not a substitute for missing delivery capacity, day-to-day IT support or permanent ownership of every design decision.
What success looks like
Clear decision rights, a practical architecture backlog, a target/transition view, better vendor challenge and stronger internal capability rather than dependency on the interim advisor.
How soapplied approaches the question
I would not start by assuming the stated problem is the whole problem. The first step is to understand the people, purpose, constraints and interactions around it, then test what intervention would improve the system rather than merely optimise one component.