Should we support ongoing communist (mostly Maoist) rebellions in the Philippines, Turkey, India, (I think) Nepal, etc?

This is a difficult question to answer because there are multiple groups in each of those countries and there are different ways one could support them. Also the multiple groups may dislike each other. Also it's generally a good idea to do specific research before supporting one.

For example, what would it mean to support Naxalites in light of considering support for CPIM? Sometimes Naxalites and CPIM members have killed each other and there are many disagreements about tactics and how capitalist-friendly the other one ultimately is.

I would recommend doing a lot of research and seeing what aligns best with your concept of what will work in their country. And if oosdibke, find and read the writings of people there and talk to communists who visit your country.

As always, default to skepticism towards liberal or ultra criticicisms of communists.

does it matter? if their movement is strong they dont need a westoid's opinion

support how? like is your org gonna raise money and donate? would that even make a difference? or are u asking if u should be happy for their victories or not give a shit? if u cant do much u probably shouldn't think about it too much, either way just look at what they are upto and decide in a per case basis, that the only thing u can do.