so what - many immi offices use wrong terminology re. extensions for example.. Many call it a visa extension but it is in fact an extension of the permission to stay. When a permission to stay is expired some offices say "your visa is expired" and that's nonsense.
if a link is not allowed (?) then Google tdac Thailand - look for a site that begins with https - ends with ". go. th" and contains tdac. immigration - that's the official site
actually not in this context - it should have been understand - not understood. you can't mix present and past time. Then it should have been "we would have understood" - but since he uses present it's "we can understand" and variations thereof - for example "we would have been able to understand"