I agree with Marcus's suggestion to delete this entry and add 三鞭酒 as an ateji form to シャンパン. I'm not seeing any evidence that it's read さんべんしゅ when referring to champagne.

世界大百科事典 薬酒 entry
。蛤蚧酒はトカゲを漬け込んだもので，3種の動物の陽根をつけるという三鞭酒（サンピエンチユウ）などとともに，強精剤としての効果を信ずる人も多いという。

I 'm really not seeing a good case for splitting here. No source has さんべんしゅ. Several do have シャンパン (or rather, mention this kanji in their シャンパン entries) The rakuten/amazon listings aren't reliable. The drink referred to is an (at least in Japan) very obscure Chinese drink which doesn't seem to have anything to do with champagne, and is maybe actually read サンピエンチュウ. Now that we have rK, why not use it?

We've been thrashing this around for years. We settled on the two-entry approach in 2017, and I still think it's the cleanest. I'd like to keep さんべんしゅ there somewhere, which would make consolidation messy. I think the  しゃんぱん reading can go.

@@ -5,0 +6 @@
+<ke_inf>&ateji;</ke_inf>
@@ -9,3 +9,0 @@
-</r_ele>
-<r_ele>
-<reb>しゃんぱん</reb>
@@ -17 +15 @@
-<gloss>Champagne</gloss>
+<gloss>champagne</gloss>

That specifically is a Chinese product though, doesn't look to be related to actual CHampagne. (the listings don't mention シャンパン etc.)
I'd drop the reading or actually delete this entry and include it as a [rK,ateji] on the main シャンパン entry.