I have been using JSL (on Windows) since 2000 when JSL first came out. The only behavior I have seen on previous versions is described below. If I hover over a variable that has been run, the last value is shown as hover help (a tool tip) and in the status bar. See attached .PNG file.
If your script window is not large enough, the status bar value is not shown. Also, note in the picture I declared two variables (a and b) as local. Once run (outside of the local function) those variables no longer have a value.
If I want to see the value in the log, I select the variable and click run or Ctrl+R and the log will show the value. In no other version, have I been able to see the value in the log without running it. I typically use hover.