There is some evidence for British tampering with Hindu scriptures, though not direct evidence:
In 1784, the famous Indologist Sir William Jones wrote the following
letter to Sir Warren Hastings, Governor General of India, confirming
our suspicions that this was indeed part of their program:
“As to the general extension [spreading] of our pure faith
[Christianity] in Hindoostan [India] there are at present many sad
obstacles to it… We may assure ourselves, that Hindoos will never be
converted by any mission from the church of Rome, or from any other
church; and the only human mode, perhaps, of causing so great a
revolution, will be to translate into Sanscrit… such chapters of the
Prophets, particularly of ISAIAH, as are indisputably evangelical,
together with one of the gospels, and a plain prefatory discourse,
containing full evidence of the very distant ages, in which the
predictions themselves, and the history of the Divine Person (Jesus)
is predicted, were severally made public and then quietly to disperse
the work among the well-educated natives.” (Asiatic Researches Vol. 1.
Published 1979, pages 234-235. First published 1788).
One such work suspected of British Tampering is Bhavishya Purana where Sanskrit verses about Jesus could have been inserted by the British.
More than tampering with scriptures they concocted false racial theories using deliberate misinterpretation of scriptures which is playing havoc even to this day.
For example, "caste" was an invention of the European colonists. They corrupted Varna-Jati-Kula system into caste. Read more about it in this article. Also Aryan Invasion Theory was invented by misinterpretations of Rig Veda. The book "The Rigveda - A Historical Analysis" by Shrikant G Talageri points out some of these misinterpretations such as racially classifying Indian Jatis based on nasal index using a single word in Rig Veda, etc.