platex-dev uses the e-uptex engine

[Hironobu Yamashita]

One more note: platex will soon run on euptex but the main behavior
will not change (thus no Unicode), because the euptex engine has
"legacy-encoding-compatibility mode"

> As \forcecjktoken is now defined hyperref no longer forces
> unicode=false and the bxjsbook class  errors in platex-dev:
> 
> https://github.com/latex3/hyperref/issues/283

I think we can discuss on GH, not on tex-live list.

Best,
Hironobu