for what it's worth, the japanese wikipedia page of 愛国心 distinguishes it from nationalism (and vice versa)

I agree with Stephen. I'm not convinced this entry is improved by adding "nationalist".

@@ -13,2 +12,0 @@
-<gloss>lover of one's country</gloss>
-<gloss>nationalist</gloss>

My impression is that people would use a word like "愛国心" to distance themselves from the unsavory associations of words like "国家主義." I wouldn't be surprised if 右翼団体 groups also used the word to disingenuously distance themselves from their own views. "Patriotism" works that way in English too. The point is that both types of groups are using "愛国" specifically because they believe it will be interpreted differently or more favorably than "nationalism."

I guess it wouldn't hurt to have it as a secondary gloss, but I'm not sure it's really necessary either.

@@ -12,0 +13,2 @@
+<gloss>lover of one's country</gloss>
+<gloss>nationalist</gloss>

I think that if you look up definitions of "patriot" and "nationalist" respectively in various dictionaries, it becomes cery hard to argue that 愛国者 can be translated as one and not the other. Collins for example has "Nationalist means connected with a person's great love for their nation. " However, "patriot" has more posiive connotations at last in AmE but I would argue that 愛国者 does not in Japanese, but sort of imply association with a right-wing ideology that many find unsavoury. 右翼団体 in Japan will describe themselves as 愛国主義 rather than 国家主義, but they are normally described as "nationalists" in English.