Maintaining muscle isn't a consequense of "reducing reps and sets but keeping the intensity of the reps up", maintaining muscle during weight loss depends on doing adequate work volume on intensity high enough to cause substantial MU recruitement while eating adequate amounts of protein.
Keeping intensity up=substantial MU recruitment, no?
And protein no one can do anything about for the OP's situation.
Losing weight is dependent on calories consumed vs calories burnt. Rep numbers don't come into it.
... And higher reps causes more calories burnt, yes?