Just what I would have done.

I think "complain" and "whine" are ok if they are placed 
toward the end of the definition.

@@ -23,0 +23,2 @@
+<gloss>to complain</gloss>
+<gloss>to whine</gloss>

As Jim says, "whinge" is used quite widely. I question that "kvetch" is slang (language not accepted for dignified 
use). It's used in "Microstyle: The Art of Writing Little" by Christopher Johnson, for example, to describe what 
people do on Twitter. Sure, it's informal, but ぐちをこぼす is too.
"Other times they use it more like the watercooler, to kvetch about their jobs and their clients, discuss the news, 
gossip about celebrities, and otherwise engage in ..."
.
There is no indication in Webster, Wiktionary or Encarta that "kvetch" is considered slang. It's not like the verb 
"total", for example:
(transitive, US, slang) to demolish; to wreck completely. (from total loss)
"Honey, I’m OK, but I’ve totaled the car."
[Wiktionary]
.
ぐちをこぼす means
言ってもどうにもならないことを言って嘆く。
according to
http://dic.yahoo.co.jp/dsearch/0/0na/05084600/
.
I suggest that "whinge" and "kvetch" are closer to this than "complain" and "whine".
.
"complain" is a broader term which is often used when one is being assertive and intends to achieve redress 
(unlike ぐちをこぼす).
.
By the way, the person whom I quoted 
> "to whinge" ... is best translated into American English with "to kvetch" and into Japanese with "guchi o kobosu"
is Roger Pulvers, the 2013 winner of the Noma Award for the Translation of Japanese Literature.
"Pulvers wins Noma translation prize"
http://www.japantimes.co.jp/news/2013/04/18/national/pulvers-wins-noma-translation-prize/#.UeydRdKBmfY

@@ -20,2 +20,0 @@
-<gloss>to complain</gloss>
-<gloss>to whine</gloss>
@@ -24,0 +22,1 @@
+<gloss>to gripe</gloss>

Well, it's often classified as "British English", but it's used in Aus, NZ, Sith Efrika, etc.

whinge is British and kvetch is slang.

@@ -17,0 +17,1 @@
+<pos>&exp;</pos>
@@ -19,0 +20,2 @@
+<gloss>to complain</gloss>
+<gloss>to whine</gloss>