[:">] I saw many boards full of spam robots… Here only the forum is the spam robot. [:">]
That has no price…

Seriously, I don't think it would be easy to get help and documentation for this old Vietnamese forum to migrate to something more modern, without losing the old threads, encoding, attachments and stuff.
It would at least be a full-time job and a full rebuild, but for how long, what result? Sometimes you know what you're losing, not what you're gaining.