What'd I just read?
DD1: Cure plz.
DD2: Cure plz.
DD3: I need haste.
DD1: I need erase.
DD2: Cureeee I'm dying!
DD3: You still haven't haste me!
The fact that you used the term "constant communication" on WHM shows that something is wrong....just wrong. Maybe the fact that WHM in /shout pt needs "constant communication" for heals, is the main reason why majority of the player would rather not make /shout pt for anything.
Oh and btw, even if for some reason you do need DDs to yell at you for -na/haste/cures, it's entirely doable with auto-translate. Further more, if you can understand the meaning of JP /shout, fat chances are you can understand basic term such as haste/-na/sacrifice in JP.
Ideally, you don't want DDs to use /p chat to talk to WHM at all. Sorry to be blunt and mean, but I can kinda tell why you have hard time joining /shout, while good WHMs(that doesn't need "constant" communication for heals) got spammed with delve /tell when ppl are making delve pt.
All I see is, tons of excuses for the lack of pt and more excuses after another. While other players, such as WHM that doesn't require "constant communication" for heals get pt invite by playing better, or other ppl just spend some time learning basic JP and at least try to get into JP pt. I'm not saying you'd always be successful when you try to get into JP pt, but at least it's worth trying before worrying about JP player can't tell you how to cure in English.
Edit: Btw, if you're going to continue making excuses, I'd rather not to reply anymore. I'm not saying I can play WHM perfect, but at least I wouldn't make a shit tons of excuses for no invite. If DDs needs constant communication for heals when I'm on WHM, the first thing I'd worry about is to play WHM better, not the amount of /shout on the server.