Hindu-ism is an exonym applied by Britain to group the religions of Bhaarat, which was also known as Hind to the Persians, and Indus to the Greeks and India to the Anglicans.
It is therefore a non-existent religion. The religions must be addressed by their own names.
However, the label had been useful in describing the compatible and shared nature of the local religions. I propose instead that they be defined by another term to describe the compatible nature of all the religions that exist and all that will come up in the future. But Sanaathana Dharma is not the right word, since it leads to debates on which Dharma is Sanaathana.
I propose that the term should be “non-exclusionary religions according to [some label]“. Sort of like a constitution.