Indian legal documents

This is so called "legalese". A dialect used only in contracts, law documents and other court and law related sources. Not only it's valid English, it's written in such a way as to not leave any ambiguities, or room for interpretation, using phrases that don't occur in everyday English, but have specific properties of describing places, moments, locations without leaving room for ambiguity. "Whereas", "Herein" or "thereof" are quite uncommon in normal English, but abundant in legalese.

Think of it more like english-as-computer-language, than english usable for speaking; a trained lawyer can understand it fluently but it's very difficult to read for normal people. Ambiguous wording could be challenged in court — arguments about that can drag into months until the opponent drops the case discouraged by the opposite side taking every entry open for interpretation the opposite way it was intended, so lawyers use so called "boilerplates", document patterns used over and over, that were tested in court as leaving no doubts or ambiguities exploitable by opponents, and just fill in the plaintiff names, dates, objects of the cases, and submit that to the court or file away as legally binding contracts.

Answering:

1. Yes, that's used pretty much everywhere. People who use a different language in their legal documents open themselves to irrelevant, lengthy attacks when using these in court — a tactic to wear off the opponent by dragging the case indefinitely becomes viable.

2. As far as I know, "legalese" evolves much slower than mainstream English, so yes, a very similar language was used 100 years ago. Not only that, lots of words that fell out of use of mainstream English still live through legalese, their contemporary counterparts being more ambiguous, or just through tradition.

3. It's correct, though horrible English. Grammar errors are an invitation for discussion "what the author intended", "what the sentence should mean" and as such, avoided at all cost. Still, the style (e.g. repetition, run-on sentences) is completely disregarded in favor of adherence to the "boilerplate".

This kind of abstruse legalese is intentionally incomprehensible. It has been regularly used by lawyers for centuries. It may very well be grammatically correct & meaningful, but what it means requires knowledge of the terminology & legal conventions of the country it was written in.

It isn't the language used everywhere in the Anglophone world these days. In the USA, contemporary legalese isn't always so difficult to understand. I don't know about other Anglophone countries, but I did study contract law and legal writing at an American law school. Even what is now supposed to be clear and easy-to-understand legalese is often very difficult to understand, but usually not this bad.

Calling it wrong implies two judgments.

One is a judgment on the grammatical correctness of the language. It probably is grammatically correct. This kind of language is often called boilerplate in the US. That means that it's standard and traditional.

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Another is a moral judgment about whether this kind of language should be used in legal documents. I'd say it's morally wrong because it's self-serving. Rather than make the contract clear to those who sign it, this kind of language serves only to require that they pay lawyers to read and argue about its meaning. The lawyers who write these documents, in other words, are what some economic theories call "job creators"; i.e., they intentionally create jobs for themselves and other pettifoggers by writing legal documents in a kind of secret code whose meaning must be argued over in a courtroom by lawyers and then decided upon by a judge and jury.