I doubt it.
Many of India’s royal families, who’ve been tutored by Englishmen, also have similar accents.
Besides, the article speaks of other similarities, too.
Of course ~ all the Indo-European languages derive from the same sources. Even Englisha and Russian share the same sounds but they use them in different ways ~ but the Welsh predominance in the colonial service AND as English teachers in India is nothing to be sniffed at.