questions that pertain to bringing the dead back to life, atonement for killing a cat etc. In general, treating violations of modern science in Hindu scriptures as factual instead of metaphorical.
First of all, I'm not sure what obscurantism has to do with any of the points you're making. Obscurantism means "opposition to the spread of knowledge" or "a style characterized by deliberate vagueness or abstruseness". But let me respond to your points all the same.
questions that pertain to bringing the dead back to life
There is nothing wrong with questions about this; it has to do with Siddhis or magical powers, a topic discussed in Hindu scripture.
atonement for killing a cat
This too is a subject discussed in Hindu scripture, and there is nothing wrong with questions about it.
In general, treating violations of modern science in Hindu scriptures as factual instead of metaphorical.
This site doesn't impose a particular view of Hindu scripture on its members. You can believe (as I do) that everything in Hindu scripture is literally true, or believe that some or all of it is symbolic, or you can even be a non-Hindu, and still contribute productively to the site.
Things like Valmiki Ramayana 5.1.123- “O son! Earlier in the Krita yuga, mountains had wings. With speed equal to that of Garuda and Vayu, they went in all directions. After that when those mountains were thus flying freely, Devas and living creatures together with sages obtained fear in the doubt that those mountains might fall down. Then the angry Devendra who performed a hundred Asvamedha rituals, cut off the wings of thousands of mountains by his weapon vajra then and there." If the rules are that this has to be treated as literal truth - this board is contributing to Hinduism's death.
No, this doesn't have to be treated as literal truth, but it can be. If someone posts a question or answer treating this as literal truth, that is absolutely fine. If someone posts a question or answer treating this as symbolism, that's allowed too, but if you're making claims like "this symbolizes this", you should back up your claims with sources.
Can questions/answers regard things that go against modern science as metaphors? Vishnu purana has drastic errors about the distance from the earth to the sun and the moon, you are not going to say that those statements shouldn't called wrong?
You are allowed to treat anything and everything in Hindu scripture as metaphors, but again if you're making a specific claim that something is a metaphor for something, you should back it up with sources.
contributors to this board in 2017 use the word "shudra". They are seriously harming Hinduism
Well, like it or not, that is part of Hindu terminology, and thus perfectly allowed on the site.
things like Manu smriti XII. 4. "If the shudra intentionally listens for committing to memory the veda, then his ears should be filled with (molten) lead and lac; if he utters the veda, then his tongue should be cut off; if he has mastered the veda his body should be cut to pieces." should be roundly condemned.
First of all that's from the Gautama Dharma Sutras, not the Manu Smriti. But in any case, this site does not require its members to condemn any part of Hindu scripture. Now if you would like to post an answer saying that some rule in the Manu Smriti should not be followed, for instance on the basis of quotes by Swami Vivekananda, you're free to do so, but others are free to post answers quoting such rules.
A forum like this shouldn't have any sacred cows and should try to discover new insights into Hinduism without being bound by what has been written in the past.
That's not what this site is for. We're not here to make new discoveries, but to create a knowledge base about what is already known about Hinduism.
It is perfectly possible to be a devout Hindu and refuse to literally believe everything in scripture.
Yes, there are Hindus who treat some or all of Hindu scripture is symbolic, and they are allowed on the site just like Hindus who treat it all as literal.
If people still want to discuss things like India having flying machines in the past and brahmastra being an ancient nuclear weapon - these questions have to be marked somehow.
Let's distinguish between two things. If someone asked a question about whether Brahmastras are nuclear weapons, that would closed - speculation about how Hindu scripture prefigures modern science is not allowed here, and we have a dedicated close reason for that. But if someone asked a question about Brahmastras or Vimanas, without trying to make a comparison to modern science, that would be absolutely fine, and would not need to be "marked" in any way.
There have been enormous developments in science and also almost unlimited access to Hindu scriptures in English Hindi and so forth. A forum like this shouldn't have any sacred cows and should try to discover new insights into Hinduism without being bound by what has been written in the past. It is perfectly possible to be a devout Hindu and refuse to literally believe everything in scripture.
If people still want to discuss things like India having flying machines in the past and brahmastra being an ancient nuclear weapon - these questions have to be marked somehow. My suggestion is "obscurantist".