If we use temporary tables which are supposed to be created by each session of Oracle, is there a possibility that some records a user makes in one temporary table can interfere in another user’s process when he is using the same temporary table ?

Appeon for .NET version:

Appeon can be configured to connect to the database in same manner as PowerBuilder in C/S.  Simply check the “Dynamic Connection” option and uncheck the “Connection Pool” option in the connection cache configuration of the AEM (Appeon Enterprise Manager).  The username/password for each user to connect to the database must be assigned to the LogID and LogPass properties in the PB application.

Appeon for  JBoss

In PowerBuilder application (client/server), once the client establishes connection to the database, a unique session will be created in database and maps to the application session, this is so called long connection, so it's a one-to-one relationship. However on Web application (browser/server), it uses the connection cache to connect to the database, one Appeon IE session maps to more than one session in the database; when data retrieval or procedure is executed, the cache pool will automatically allocate a connection to connect to the database.  When transaction is completed, the connection will be rolled back to the cache pool, this is so called short connection. One Web application may have many transactions, so it's a one-to-many relationship.

So you need to check your temp table syntax, if the temp table is the database session level, when the connection go back to the cache pool, the temp table will be deleted which will caused you can’t use the temp table again.