日本語訳のリリースノートのリンクをまとめます。

4.8
https://docs.unrealengine.com/latest/JPN/Support/Builds/ReleaseNotes/2015/4_8/index.html

4.7
https://www.unrealengine.com/ja/blog/unreal-engine-47-released
https://docs.unrealengine.com/latest/INT/Support/Builds/ReleaseNotes/2015/4_7/index.html

4.6
https://docs.unrealengine.com/latest/JPN/Support/Builds/ReleaseNotes/2014/4_6/index.html

4.5
https://docs.unrealengine.com/latest/JPN/Support/Builds/ReleaseNotes/2014/4_5/index.html

4.3
https://docs.unrealengine.com/latest/JPN/Support/Builds/ReleaseNotes/2014/4_3/index.html

4.2
https://docs.unrealengine.com/latest/JPN/Support/Builds/ReleaseNotes/2014/4_2/index.html

4.1
https://docs.unrealengine.com/latest/JPN/Support/Builds/ReleaseNotes/2014/4_1/index.html