\definefontfeature
  [hebrew]
  [mode=node,
   language=dflt,
   script=hebr,
   fina=yes,
   init=yes,
   isol=yes,
   medi=yes,
   mark=yes]

\definefont[test][file:micross*hebrew]

\starttext

    \startTEXpage

        \test \righttoleft  יִשְׂרָאֵל \quad בָּיִת שֶל אָבִי

    \stopTEXpage

\stoptext
