I also think your focus on making performance more predictable and reducing the mental burden on devolopers who want to write reliably fast code is exactly the right one; even a version of luajit that's half as fast on average but more predictable could be more useful in practice to most people.
Having said that, to keep some already precarious and fringe technology alive by adding as core part of the toolchain an app written in an even more fringe and decidedly more fiddly[*]/unstable language like Pharo, and one which has basically zero community overlap with luajit users seems... bold.
As does moving forward by adding R/codegen targetting pharo to the mix.