I don't think we need more than one gloss for obscure カタカナ語 like this.

@@ -15 +14,0 @@
-<gloss>the opposition</gloss>

We add such cross references when they make sense, but I'm not really seeing how this would be a solution to the problem you're seeing here. It's probably 
better to tag entries that are obscure as [obsc] (or [obs], [arch], [dated]) and let apps and sites use that info + our frequency tags to make reverse 
searches bring up the most relevant entry on top and perhaps hide some others. (jisho.org does not currently hide entries that are tagged obsc from 
reverse searches. If you think they should, it'd be best to take it up with them.)

I've suggested implementing an explicit "more commonly as" type of xref on the Github, which by the way is a better place to discuss topics that concern 
policy than the comment section of an individual entry. 
https://github.com/JMdictProject/JMdictIssues/issues

If you come across any other obscure katakana words you think should have xrefs to more common words with similar meaning or be tagged as [obsc], go ahead 
and edit them.

Thank you for the reactions. I understand the notion of including obscure terms as long as they’re well-documented. However, in that case, 
wouldn’t it be a good idea to try and more actively add cross references if it’s an obscure katakana entry, in order to avoid learner confusion as 
I described in my previous comment? I’m not saying every katakana term has a “Japanese” equivalent; katakana terms are very much Japanese 
themselves and they can have different nuances than their “equivalent”, so a cross reference would not always be in place. But again I’m trying 
to look at it from the perspective of language learning and user friendliness.

It's also in 現代人のカタカナ語辞典 and mentioned 
in daijs' オポジション entry. To try and answer 
Tsuchida's question: we don't add words like 
this unless there's some evidence they're 
being used or appear in some other dictionary 
or work of reference. We don't avoid obscure 
or outdated words if their usage is well-
documented.

More commonly as xref

@@ -11,0 +12 @@
+<xref type="see" seq="1537580">野党</xref>

ルミナス
0 n-grams

It'gets a little use and it's a sub-entry in ルミナス. Best to keep it and tag it as not common.

@@ -11,0 +12 @@
+<misc>&obsc;</misc>
@@ -12,0 +14 @@
+<gloss>the opposition</gloss>