If I were them, I think I might be tempted to (still) stick closer to 240V (if not higher - see below), thereby giving more scope for VD before the voltage supplied to consumers becoming less than the 'permitted minimum'.
In fact, I would have thought that the voltage output from the tranny (and, indeed, supplied to the closest consumers) would already be a fair bit above 240V, so as to keep the most distant consumers above the minimum at times of high load, wouldn't it?
That would make good sense, I just wonder if the new sub transformers output 10 volts less than the old ones in order to accommodate the new 230v vs the old 240V nominal?