News: KLL Kalium Lakes Ltd Says Overall Beyondie Sop Project Is 75% Complete, page-38

The reality is we don't know what the Fx will be in April and we don't know what SOP price they will achieve.
KLL always used the highest SOP pricing in their modelling (followed by APC). The May revisions gave them the most favourable Fx in the sector but at least they had the sense to use realistic SOP pricing.
Your assumptions may be correct, all we can accurately say at the moment is that the Fx has moved significantly against KLL and may move further. Hopefully the SOP prices have moved in a favourable direction to offset the Fx.
I am sure that start up is an inexact science with lots of variables in the mix.
The worse case scenario is a cash shortfall and we know what that means. A prolonged rise in the Aussie in the absence of a higher SOP price is going to have implications regarding funding the next phase and stage. Of course this is all speculation and shouldn't come as a surprise to anyone.