It is a 15 AMP breaker. Would like to put a 20 AMP breaker there but I don't think this is safe at all. The house wiring is solid copper instead of multi-conductor. Don't know the wire gauge. I am guessing 16 or 18.
PR follows the NEC.
16 or 18 ga wire should not be used. 14 is the smallest allowed. Except for larger cables, most residential wire is solid
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The breakers you have are notorious for not tripping. While failure is uncommon on modern breakers, it is common with the breakers you have.
However, since the breaker is actually tripping, it's probably just doing it's job. The most likely scenario is the circuit is in fact overloaded.
You need to have the circuit load tested.
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