2016 Ford Fusion 2.5L – Radiator internal cooler failure, coolant contaminated with transmission fluid – risk of engine damage?

Hi,
I’m looking for a professional opinion before deciding whether to proceed with repairs or cut my losses.
Vehicle: 2016 Ford Fusion SE, 2.5L naturally aspirated engine (not EcoBoost).
The car was recently taken to a dealership for an overheating concern. An independent mechanic has since diagnosed the following:
• Coolant recovery tank contaminated with transmission fluid
• Radiator has an internal transmission cooler that failed internally, allowing fluid crossover
• Transmission fluid was found to be low and dirty
• No white exhaust smoke
• No sludge found outside of the cooling system
• Vehicle drives normally at present
Recommended repairs are radiator replacement, coolant system flush, transmission service, and re-test.
The mechanic states there are currently no obvious signs of engine failure, but also cannot guarantee long-term engine health until contamination is fully resolved.
My question is:
In your experience, how often does this type of failure result in delayed engine failure after repairs are completed?
Is it reasonable to expect additional usable life from this engine if the repair is done promptly?
Are there any specific red flags I should watch for after the repair that would indicate internal engine damage?
I’m trying to make a financially responsible decision and would appreciate any professional insight.
Thank you.