What a bizarre scenario!
The helicopter doesn't know it is in a microburst, and therefore this will not affect your ability to attain auto and maintain RRPM. Hence, the answer to your question is:
YES - if you react correctly.
The above does not address the situation of transiting through the windhear area: ie experiencing an engine failure moments before passing from stable air into the microburst area. That would be intresting.
When in the microburst, it will not affect your ability to attain auto and maintain RRPM, but the ground might! Since the majority of microbursts occur close to the ground, you may not have time to react, and even if you did, and the microburst you are experiencing is tavelling downwards, you rate of descent relative to the ground will be huge, and as you enter your flare, you will probably be experiencing a significant tailwind as well.
High groundspeed, high rate of descent: no thanks (you really would need the "super-spine"!!
)