No they're issues: if it was easy, then no one would bother with HVDC - HVDC exists because it reduces losses and vastly eases grid coordination because convers

No they're issues: if it was easy, then no one would bother with HVDC - HVDC exists because it reduces losses and vastly eases grid coordination because conversion to and from AC at either end is handled under local control and can be totally independent of the source/destination. Its the difference between just shifting the frequency or phase on your local control clock at the substation, and trying to coordinate with another state/territory/nation's entire AC generation infrastructure to keep everything in phase.