As an NES but not a teacher, "should be regarding" is fine by me, but I would personally have used "should regard/consider".
Regards
R21

Student or Learner
We Hindus should regarding Persian as an Indian language since it was of the Parsis and of Kaikeyi and Islam appropriated it after conquest.
It was a tweet of a person! I think it should be "Should be regarding", he would have probably left it out by mistake! Or can we write in this way?
As an NES but not a teacher, "should be regarding" is fine by me, but I would personally have used "should regard/consider".
Regards
R21
We Hindus should regard/consider Persian as an Indian language, since it was the language of the Parsis and the Kaikeyi until it was appropriated by Islam after the conquest.
I assume that your readers know which conquest is meant.
The problem with Twitter is that tweets are limited to a maximum of 140 characters. Don't expect grammatical English. In your example, however, I would say it was either a typo or written by a non-native. My guess is that it was tweeted by a speaker of Indian English in which "we should be regarding" is quite natural, and he/she just missed out "be".
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
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