Apply more code review suggestion:

* use more specific localization key
* decouple internal localized error message from external localization

src/main/resources/fxml/health_start_fail.fxml

@@ -4,11 +4,12 @@
 <?import javafx.scene.control.Button?>
 <?import javafx.scene.control.TextArea?>
 <?import javafx.geometry.Insets?>
-<?import org.cryptomator.ui.controls.FormattedLabel?>
 <?import javafx.scene.control.TitledPane?>
 <?import org.cryptomator.ui.controls.FontAwesome5IconView?>
 <?import javafx.scene.layout.Region?>
 <?import javafx.scene.layout.HBox?>
+<?import javafx.scene.text.TextFlow?>
+<?import javafx.scene.text.Text?>
 <VBox xmlns="http://javafx.com/javafx"
 	  xmlns:fx="http://javafx.com/fxml"
 	  fx:controller="org.cryptomator.ui.health.StartFailController"
@@ -19,9 +20,12 @@
 		<Insets topRightBottomLeft="12"/>
 	</padding>
 	<Label text="%health.fail.header" styleClass="label-large" />
-	<FormattedLabel fx:id="ioErrorLabel" format="%health.fail.ioError" arg1="${controller.localizedErrorMessage}" visible="${controller.ioException}" managed="${controller.ioException}"/>
+	<TextFlow fx:id="ioErrorLabel" visible="${controller.ioException}" managed="${controller.ioException}">
+		<Text text="%health.fail.ioError" />
+		<Text text="${controller.localizedErrorMessage}"/>
+	</TextFlow>
 	<Label fx:id="parseErrorLabel" text="%health.fail.parseError" visible="${controller.parseException}" managed="${controller.parseException}"/>
-	<TitledPane fx:id="moreInfoPane" text="%health.fail.moreInfo" expanded="false" contentDisplay="LEFT" >
+	<TitledPane fx:id="moreInfoPane" text="%health.fail.moreInfo" expanded="false">
 		<graphic>
 			<HBox alignment="CENTER" minWidth="8">
 				<FontAwesome5IconView glyph="${controller.moreInfoIcon}"/>

src/main/resources/fxml/vault_options_general.fxml

@@ -41,7 +41,7 @@
 			<ChoiceBox fx:id="actionAfterUnlockChoiceBox"/>
 		</HBox>
 
-		<Button fx:id="healthCheckButton" text="%vaultOptions.general.startBtn" onAction="#startHealthCheck">
+		<Button fx:id="healthCheckButton" text="%vaultOptions.general.startHealthCheckBtn" onAction="#startHealthCheck">
 			<graphic>
 				<FontAwesome5IconView glyph="STETHOSCOPE"/>
 			</graphic>

src/main/resources/i18n/strings.properties

@@ -319,7 +319,7 @@ vaultOptions.general.actionAfterUnlock=After successful unlock
 vaultOptions.general.actionAfterUnlock.ignore=Do nothing
 vaultOptions.general.actionAfterUnlock.reveal=Reveal Drive
 vaultOptions.general.actionAfterUnlock.ask=Ask
-vaultOptions.general.startBtn=Start Health Check
+vaultOptions.general.startHealthCheckBtn=Start Health Check
 
 ## Mount
 vaultOptions.mount=Mounting