I extracted metadata using isql -a > metadata.sql. After editing the create
line, when I try to rebuild the metadata via isql -i metadata.sql it creates
the database but chokes on:

CREATE DOMAIN BOOLEAN AS CHAR(1)
Default 'N'
( Check (Value in ('N','Y')));


Here's the error:

Dynamic SQL Error
-SQL error code = -104
-Token unknown - line 3, char 10
-(
Statement failed, SQLCODE = -607

I verified that this is the line by changing it to:
CREATE DOMAIN BOOLEAN AS CHAR(1) Default 'N'
( Check (Value in ('N','Y')));

At which point the error line changes to 2 ;-).

This sounds like a bug, I checked the bug tracking system and didn't find
this specific issue (some that looked similar though).