I agree. I meant to delete it in the last edit.

@@ -12 +11,0 @@
-<xref type="see" seq="2844866">安らかにお眠りください</xref>

What's the point of the  安らかにお眠りください xref? I think there's too many random xrefs being added recently. I think it will only make things confusing for users.

We don't usually use the general sense note to indicate other related forms in that way. If they are worth mentioning they should be made entries.

@@ -18 +18 @@
-<s_inf>usu. as translation of English or Latin. also 〜眠ってください, 〜眠ってれ、〜眠ってね, etc.</s_inf>
+<s_inf>usu. as translation of English or Latin</s_inf>

More common than this form (ください variants, without keigo お, so sharing the same 安らかに眠 prefix as this term）:
安らかにお眠りください　11894
安らかにお眠り下さい　　6733
安らかに眠ってください　7414
安らかに眠って下さい　　4138	  

This form:
安らかに眠れ	9740	 <- imperative direct 眠れ

安らかに眠ってね	2197	  Friendly imperative ってね
安らかに眠ってくれ	1899	  Friendly imperative (step down from kudasai)

Here is an explicitly Christian usage ("went to heaven") with the friendly 眠ってね form.
(warning, young woman, sad post)
https://twitter.com/hoshina_mizuki/status/1131520280076070913

lots of pets get this form as well.

Explanation of differences and dangers careless mix/match of 安らかに眠れ and ご冥福をお祈りします. (I have no idea how offended any Japanese person would be in practice with screwing this up, but at the death of someone's loved on, it's probably worth attempting to handle this with care)
https://www.e-denpo.net/column/a045
冥福 is buddhist: そもそも「ご冥福」とは、仏教に基づいたお悔やみの言葉です。「冥」は死後の世界（冥土）、「福」は幸福のことを表し、「ご冥福」は故人の死後の幸せを指す言葉として使われています。
安らかに眠れ is christian: キリスト教の場合、...「安らかなお眠りをお祈り申し上げます」「平安をお祈り致します」「安らかな旅立ちになりますよう、心からお祈り申し上げます」

In the case of this aquarium seal, I guess the farewell reflects the religion of the commenter over the religion of the seal (we see both expressions):
https://twitter.com/TOBA_AQUARIUM/status/1608357296735649792
1. クチャちゃん🦭どうか安らかに。 <---- here's one I haven't covered. I've seen the どうか prefix elsewhere as well.
2. クチャさん安らかにお眠り下さい🙏 天国からみんなの事見守って下さい。  Includes 天国, prayer hands emoji, and 安らかに
3. ご冥福をお祈りします
4. クチャさんのご冥福を心よりお祈り申し上げます。
5. 心より御冥福をお祈りします

use site:"twitter.com" "安らかにお眠り下さい" (or whatever) to find examples if you don't have twitter search.  The pure "latin" form seems to mostly yield over references to the concept of RIP. All other forms seem to be actual fair-wells to people (or pets, etc.) who have died.

安らかに眠れ does seem to be the "pure" latin equivalent of RIP for ceremonial or marketing purposes. But it's really just a calque of the command "rest in peace", and *all* of the various Japanese command-form variations seem to exist. (って下さい、ってくれ、って、ってね), and several are more popular/practical than this one in daily use. 

Also, the internet suggests to me that this term is Christian, and "ご冥福をお祈りします" is Buddhist (which makes it the "common" term only insomuch as Japan is not a Christian nation).  Minimally adding [fld=christn] and [fld=buddh] may serve as some kind of warning that these are not strictly equivalent.

This also suggests that the entire gloss "Rest in peace" on ご冥福をお祈りします is perhaps unwise (though common), as it is essentially suggesting the wrong religion entirely. (how can "happiness in the next life" = "rest", I wondered).  Certainly for a culture-modifying localization, "Rest in Piece" is a fine day-to-day equivalent if you're talking about characters in a film, but maybe not ideal if you're addressing a Christian in Japan.  (And 安らかにお眠りください might not be great when addressing a Buddhist)

Essentially I think I'm agreeing with Robin's 2019 comment that picking the wrong term "would be a big error," but I think there is some religious nuance here, and that this term is "correct" for the (3%?) of the Christian population here. Double-checked, 1.5%.

One extra form (found on the twitter seal reference):
どうか安らかに	9055	  (often ends at に)
どうか安らかにお眠り	2126	 (but not always)
どうか安らかに眠って	1116

@@ -11,0 +12 @@
+<xref type="see" seq="2844866">安らかにお眠りください</xref>
@@ -14 +15,2 @@
-<s_inf>usu. as translation of English or Latin</s_inf>
+<field>&Christn;</field>
+<s_inf>usu. as translation of English or Latin. also 〜眠ってください, 〜眠ってれ、〜眠ってね, etc.</s_inf>

yeah, that's fair.  i definitely think it should be an entry, but the note is perhaps warranted