Thanks for the advise! For my development scope, I don't see the necessity to maintain 2 time manner. I could change my system timezone for this situation as last resort. As I do not need the timezone auto convert in this way. However, I am looking if there's any Perl way can do this.
For more real case, I do not hesitate to do the conversation, but rather reserve the timezone for public users' own tz for their own location( not my system ). Writing log or so is just one example, out of many scenarios.