As discussed before, we are investigating this but it's a little trickier than it looks. This functionality needs to work at all times, including offline when the public address book information may or may not be available.
Using the DB title as a source for name information is pretty accurate and we allow many variations on the name/internet address them. All the standard Lotus separators are supported along with shortnames. If these are changed away from those that would be the default though, then results may not be perfect.
If we're going to do a lookup, we need to ensure there is a lookup source!
As this is a core functionality change it won't be fixed in OpenNTF ME 6.5.3 but will be considered for 6.5.4.