I came to know that Swami Vivekananda told that there are some inconsistencies or prakshiptas(later insertions) or errors in Hindu scriptures but he did not rectify them intentionally.
Is it true? Where did he tell the same?
Yes, obviously Swamiji mentioned it.But He did not aspire to write a new smriti Himself.I am quoting the relevant portion from 'Swami-Sishya-Samvad' by Saratchandra Chakrabarty, included in Swamiji's Complete Works:
Swamiji :Most of the Puranas, the codes of Manu and others, as well as much of the Mahâbhârata form but recent literature.
....Disciple: Sir, it is you who said just now that we must revive the ancient usages and observances within the country. How then can we think lightly of sages like Manu and the rest?
¤Swamiji: What an absurd deduction! You altogether miss my point. I have only said that the ancient Vedic customs must be remodelled according to the need of the society and the times, and passed under a new form in the land. Have I not?
Disciple: Yes, sir.
Swamiji: What, then, were you talking? You have read the Shastras, and my hope and faith rest in men like you. Understand my words in their true spirit, and apply yourselves to work in their light.
Disciple: But, sir, who will listen to us? Why should our countrymen accept them?
Swamiji: If you can truly convince them and practise what you preach, they must. If, on the contrary, like a coward you simply utter Shlokas as a parrot, be a mere talker and quote authority only, without showing them in action — then who will care to listen to you?
Disciple: Please give me some advice in brief about social reform.
Swamiji: Why, I have given you advice enough; now put at least something in practice. Let the world see that your reading of the scriptures and listening to me has been a success. The codes of Manu and lots of other books that you have read — what is their basis and underlying purpose? Keeping that basis intact, compile in the manner of the ancient Rishis the essential truths of them and supplement them with thoughts that are suited to the times; only take care that all races and all sects throughout India be really benefited by following these rules. Just write out a Smriti like that; I shall revise it.
Disciple: Sir, it is not an easy task; and even if such a Smriti be written, will it be accepted?
Swamiji: Why not? Just write it out. " — Time is infinite, and the world is vast." If you write it in the proper way, there must come a day when it will be accepted. Have faith in yourself. You people were once the Vedic Rishis. Only, you have come in different forms, that's all. I see it clear as daylight that you all have infinite power in you. Rouse that up; arise, arise — apply yourselves heart and soul, gird up your loins. What will you do with wealth and fame that are so transitory? Do you know what I think? I don't care for Mukti and all that. My mission is to arouse within you all such ideas; I am ready to undergo a hundred thousand rebirths to train up a single man.