ExtPascal may not work with the ExtJS of today.
Indeed, this is very possible: AFAIK, the ExtJS editor only keeps track (to be downloaded) of its few
latest javascript engines on the internet. So, ExtPascal (the Pascal backend driving code for ExtJS fontend javascipt engine) should work, but with a 10 years old and specific ExtJS javascript versioned engine (some people create \ historize their own backups of their own ExtJS version, on Github for example). Nevertheless, this is not the policy pursued by the ExtJS editor itself...
I suggest better look into pas2js.
I give the same advice (take a look at
pas2js), in the interests of the stability (for the future of your projects).