Support of old ess?

[LR1]

Is there any way that this plugin is able to run old ess?

[Ayuto]

You could write a plugin that emulates ES Shell syntax and functions, but I doubt that anyone will ever do that, because the effort wouldn't be worth it.

[Omega_K2]

Pretty much what @Ayuto said

You can write a parser for ess files if you want, and execute them from there, but it will be a *LOT* of work. Rewriting the scripts in python will probably be much less effort, and it will also be more effiecent to have these things in done in python. Even rewriting scripts from es-python to sp-python is quite manageable in terms of effort (and even that may take a few hours depending on the length of the script).