The H2Database creates a JDBC URL which will include escaped characters, these are processed literally by h2.
The DB URL should be something like
jdbc:h2:file:/Users/kevin/soa/5.3.0/jboss soa p 5/jboss-as/server/default/data/h2/BPELDB;MVCC=true;LOCK_MODE=3;LOG=1;DB_CLOSE_ON_EXIT=FALSE
A quick perusal of the code would suggest that
final String dbURL = JDBC_URL_PREFIX + dbPath.toURI().toString() + flags ;
needs to be changed to
final String dbURL = JDBC_URL_PREFIX + dbPath.toURL().toString() + flags ;