There is no example of 'who' in the Batavia corpus; Tugu has the single-word expression keng.
In the Batavia corpus, kilay (literally ki lay 'what sort') is always written in one word; an allomorph klay is also used. This allomorph shows that, in spite of lay 'sort' being used independently of kilay, this interrogative pronoun was on its way to become, synchronically, a single-word expression.
Source: Maurer 2011: 144
Source: Maurer 2011: 74
Source: Maurer 2011: 51