All over sudden these Sudanese are engineeers who can do what foreigners were doing.
It's not that easy. These are donor funds with conditionalities intended to curb corruption and other vices like tribalism and favoritism. It is a divided country, so how do you expect a Dinka to fairly administer aid to non-Dinkas? Even in cases where he does, would it be seen to be fair by the non-Dinkas?
There is the experience and aptitude. Just like Uhuru does not trust a non Kikuyu to give him reliable intelligence, is the same way donors find it hard to pump money in a program run by people the donor does not trust. Note that it is not just engineers but a whole range of specialists that have the education, rare expertise and experience in these matters. The most Kiir will get is an exodus of non committed funds and skeleton staff relocated to Nairobi and Loki to complete the use of already committed funds before bolting.