Preliminaries:

• Shopkeepers version: 1.4.4
• Spigot version: 1.14.3

Reproduction on a fresh and up-to-date Spigot server:

I was able to reproduce my issue on a freshly setup and up-to-date Spigot server (currently 1.14.3) with the latest version of Shopkeepers (currently 1.4.4), with no other plugins and with no kinds of other server or client mods.

The issue:

When I spawn a village, crouch and click on him, I cannot modify his name, set a price, change color or even delete him.
I put a selling villager, with a chest behind him, I'm not in creative. I did what was wrote, right clicked on the chest, I tried with quartz and cookies.
When I crouch and right click I cannot edit a thing.

Here's the logs :

[15:38:27] [Server thread/ERROR]: Could not pass event InventoryClickEvent to Shopkeepers v2.6.0
org.bukkit.event.EventException: null
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:320) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at org.bukkit.plugin.RegisteredListener.callEvent(RegisteredListener.java:70) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at org.bukkit.plugin.SimplePluginManager.fireEvent(SimplePluginManager.java:529) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at org.bukkit.plugin.SimplePluginManager.callEvent(SimplePluginManager.java:514) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.PlayerConnection.a(PlayerConnection.java:2162) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.PacketPlayInWindowClick.a(SourceFile:33) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.PacketPlayInWindowClick.a(SourceFile:10) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.PlayerConnectionUtils.lambda$0(PlayerConnectionUtils.java:13) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.TickTask.run(SourceFile:18) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.IAsyncTaskHandler.executeTask(SourceFile:135) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.IAsyncTaskHandlerReentrant.executeTask(SourceFile:23) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.IAsyncTaskHandler.executeNext(SourceFile:114) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.MinecraftServer.aW(MinecraftServer.java:898) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.MinecraftServer.executeNext(MinecraftServer.java:891) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.IAsyncTaskHandler.awaitTasks(SourceFile:123) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.MinecraftServer.sleepForTick(MinecraftServer.java:875) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at net.minecraft.server.v1_14_R1.MinecraftServer.run(MinecraftServer.java:808) [spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_202]
Caused by: java.lang.NoSuchMethodError: org.bukkit.inventory.Inventory.getTitle()Ljava/lang/String;
at com.nisovin.shopkeepers.ui.defaults.EditorHandler.isWindow(EditorHandler.java:667) ~[?:?]
at com.nisovin.shopkeepers.ui.UIListener.validateSession(UIListener.java:40) ~[?:?]
at com.nisovin.shopkeepers.ui.UIListener.onInventoryClick(UIListener.java:82) ~[?:?]
at sun.reflect.GeneratedMethodAccessor26.invoke(Unknown Source) ~[?:?]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_202]
at java.lang.reflect.Method.invoke(Method.java:498) ~[?:1.8.0_202]
at org.bukkit.plugin.java.JavaPluginLoader$1.execute(JavaPluginLoader.java:316) ~[spigot-1.14.3.jar:git-Spigot-5e4e7f3-5f88938]
... 17 more

Shopkeepers version: 1.4.4

I think you meant v2.6.0 (that's what your log says).
Anyways, you will have to update Shopkeepers to v2.7.2 in order to work with Spigot 1.4.x: https://dev.bukkit.org/projects/shopkeepers/files/2734200

Duplicate issue: #594