this was probably a bad idea because they need to be actors for events to work

Source/MyProject/Private/MagicFloatInput.cpp

@@ -15,4 +15,9 @@ void UMagicFloatInput::HandleOnTextCommitted(
     x = FCString::Atod(*inText.ToString());
 
   SetText(FText::FromString(FString::Printf(TEXT("%.7f"), x)));
+  HandleMagicFloatsMangledEvent();
+}
+
+void UMagicFloatInput::HandleMagicFloatsMangledEvent() {
+  OnMagicFloatsMangled.ExecuteIfBound();
 }

Source/MyProject/Private/VerifierTextBlock.cpp

@@ -1,5 +1,12 @@
 // Fill out your copyright notice in the Description page of Project Settings.
 
-
 #include "VerifierTextBlock.h"
 
+void UVerifierTextBlock::NativeOnInitialized() {
+  if (destInput != nullptr) {
+    destInput->OnMagicFloatsMangled.BindUObject(
+        this,
+        &UVerifierTextBlock::verifyFloats
+    );
+  }
+}