No reasons given for reversing the previous position.

@@ -3,0 +4,4 @@
+<k_ele>
+<keb>江</keb>
+<ke_inf>&sK;</ke_inf>
+</k_ele>
@@ -13 +17,2 @@
-<s_inf>indicates direction or goal; pronounced え in modern Japanese; occ. written as 江</s_inf>
+<misc>&uk;</misc>
+<s_inf>indicates direction or goal; pronounced え in modern Japanese; rarely written as 江</s_inf>

I agree with Robin. It's like 乃 or 之 for の.
I'll switch it back, add a comment, close and reopen.

@@ -4,5 +3,0 @@
-<k_ele>
-<keb>江</keb>
-<ke_inf>&ateji;</ke_inf>
-<ke_inf>&rK;</ke_inf>
-</k_ele>
@@ -15,2 +9,0 @@
-<re_nokanji/>
-<re_inf>&rk;</re_inf>
@@ -20,2 +13 @@
-<misc>&uk;</misc>
-<s_inf>indicates direction or goal; pronounced え in modern Japanese</s_inf>
+<s_inf>indicates direction or goal; pronounced え in modern Japanese; occ. written as 江</s_inf>

I think putting it in the kanji field (even as an rK form) is giving it undue prominence. None of the other kokugos mention it at all. I wouldn't mind relegating it to a note.

Interesting note in sankoku's entry for this particle.
>> 花輪や役者へのおくりものなどで「：江」とも。「○○さん江〔『賛江』とも〕・○○丈(じょう)江」

I see some questions on chiebukuro about this phenomenon.
https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q1215209622
>> 時々、贈り物に さん江って書いてあるのをみかけるのですが
https://detail.chiebukuro.yahoo.co.jp/qa/question_detail/q10117567650
>> 「～さん江」はどのような意味なのですか？
etc

@@ -3,0 +4,5 @@
+<k_ele>
+<keb>江</keb>
+<ke_inf>&ateji;</ke_inf>
+<ke_inf>&rK;</ke_inf>
+</k_ele>
@@ -9,0 +15 @@
+<re_nokanji/>
@@ -13,0 +20 @@
+<misc>&uk;</misc>