Are there known problems with 2015 Mitsubishi Triton's intercooler pipes/hoses?

The MQ Triton doesn’t seem any better or worse than its rivals in this department. But, like other makes and models, there’s a healthy aftermarket supply of replacement intercoolers and the pipework that feeds them, so it’s definitely not an unknown problem.

But your experience is exceptional. Were all five vehicles bought brand-new at the same time? If so, they’re all likely to be from the same production run which could explain a faulty batch of hoses.