diff --git a/source/tools/i18n/checkTranslationsForSpam.py b/source/tools/i18n/checkTranslations.py
similarity index 58%
rename from source/tools/i18n/checkTranslationsForSpam.py
rename to source/tools/i18n/checkTranslations.py
index 982a0292c8..072768630d 100644
--- a/source/tools/i18n/checkTranslationsForSpam.py
+++ b/source/tools/i18n/checkTranslations.py
@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 #
-# Copyright (C) 2020 Wildfire Games.
+# Copyright (C) 2021 Wildfire Games.
 # This file is part of 0 A.D.
 #
 # 0 A.D. is free software: you can redistribute it and/or modify
@@ -16,18 +16,60 @@
 # You should have received a copy of the GNU General Public License
 # along with 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 
-import os, re, sys
+import os
+import re
+import sys
 import multiprocessing
 
-from i18n_helper import l10nToolsDirectory, projectRootDirectory
+from i18n_helper import projectRootDirectory
 from i18n_helper.catalog import Catalog
 from i18n_helper.globber import getCatalogs
 
 l10nFolderName = "l10n"
 
-def checkTranslationsForSpam(inputFilePath):
-    print(f"Checking {inputFilePath}")
-    templateCatalog = Catalog.readFrom()
+VERBOSE = 0
+
+
+class MessageChecker:
+    """Checks all messages in a catalog against a regex."""
+    def __init__(self, human_name, regex):
+        self.regex = re.compile(regex, re.IGNORECASE)
+        self.human_name = human_name
+
+    def check(self, inputFilePath, templateMessage, translatedCatalogs):
+        patterns = set(self.regex.findall(
+            templateMessage.id[0] if templateMessage.pluralizable else templateMessage.id
+        ))
+
+        # As a sanity check, verify that the template message is coherent.
+        # Note that these tend to be false positives.
+        # TODO: the pssible tags are usually comments, we ought be able to find them.
+        if templateMessage.pluralizable:
+            pluralUrls = set(self.regex.findall(templateMessage.id[1]))
+            if pluralUrls.difference(patterns):
+                print(f"{inputFilePath} - Different {self.human_name} in singular and plural source strings "
+                      f"for '{templateMessage}' in '{inputFilePath}'")
+
+        for translationCatalog in translatedCatalogs:
+            translationMessage = translationCatalog.get(
+                templateMessage.id, templateMessage.context)
+            if not translationMessage:
+                continue
+
+            translatedPatterns = set(self.regex.findall(
+                translationMessage.string[0] if translationMessage.pluralizable else translationMessage.string
+            ))
+            unknown_patterns = translatedPatterns.difference(patterns)
+            if unknown_patterns:
+                print(f'{inputFilePath} - {translationCatalog.locale}: '
+                      f'Found unknown {self.human_name} {", ".join(["`" + x + "`" for x in unknown_patterns])} in the translation '
+                      f'which do not match any of the URLs in the template: {", ".join(["`" + x + "`" for x in patterns])}')
+
+
+def check_translations(inputFilePath):
+    if VERBOSE:
+        print(f"Checking {inputFilePath}")
+    templateCatalog = Catalog.readFrom(inputFilePath)
 
     # If language codes were specified on the command line, filter by those.
     filters = sys.argv[1:]
@@ -35,37 +77,22 @@ def checkTranslationsForSpam(inputFilePath):
     # Load existing translation catalogs.
     existingTranslationCatalogs = getCatalogs(inputFilePath, filters)
 
-    urlPattern = re.compile(r"https?://(?:[a-z0-9-_$@./&+]|(?:%[0-9a-fA-F][0-9a-fA-F]))+", re.IGNORECASE)
+    spam = MessageChecker("url", r"https?://(?:[a-z0-9-_$@./&+]|(?:%[0-9a-fA-F][0-9a-fA-F]))+")
+    sprintf = MessageChecker("sprintf", r"%\([^)]+\)s")
+    tags = MessageChecker("tag", r"[^\\][^\\](\[[^]]+/?\])")
 
     # Check that there are no spam URLs.
     # Loop through all messages in the .POT catalog for URLs.
     # For each, check for the corresponding key in the .PO catalogs.
     # If found, check that URLS in the .PO keys are the same as those in the .POT key.
     for templateMessage in templateCatalog:
-        templateUrls = set(urlPattern.findall(
-            templateMessage.id[0] if templateMessage.pluralizable else templateMessage.id
-        ))
-        # As a sanity check, verify that the template message is coherent
-        if templateMessage.pluralizable:
-            pluralUrls = set(urlPattern.findall(templateMessage.id[1]))
-            if pluralUrls.difference(templateUrls):
-                print(f"{inputFilePath} - Different URLs in singular and plural source strings "
-                      f"for '{templateMessage}' in '{inputFilePath}'")
+        spam.check(inputFilePath, templateMessage, existingTranslationCatalogs)
+        sprintf.check(inputFilePath, templateMessage, existingTranslationCatalogs)
+        tags.check(inputFilePath, templateMessage, existingTranslationCatalogs)
 
-        for translationCatalog in existingTranslationCatalogs:
-            translationMessage = translationCatalog.get(templateMessage.id, templateMessage.context)
-            if not translationMessage:
-                continue
+    if VERBOSE:
+        print(f"Done checking {inputFilePath}")
 
-            translationUrls = set(urlPattern.findall(
-                translationMessage.string[0] if translationMessage.pluralizable else translationMessage.string
-            ))
-            unknown_urls = translationUrls.difference(templateUrls)
-            if unknown_urls:
-                print(f'{inputFilePath} - {translationCatalog.locale}: '
-                      f'Found unknown URL(s) {", ".join(unknown_urls)} in the translation '
-                      f'which do not match any of the URLs in the template: {", ".join(templateUrls)}')
-    print(f"Done checking {inputFilePath}")
 
 def main():
     print("\n\tWARNING: Remember to regenerate the POT files with “updateTemplates.py” "
@@ -76,7 +103,7 @@ def main():
             if len(filename) > 4 and filename[-4:] == ".pot" and os.path.basename(root) == "l10n":
                 foundPots += 1
                 multiprocessing.Process(
-                    target=checkTranslationsForSpam,
+                    target=check_translations,
                     args=(os.path.join(root, filename), )
                 ).start()
     if foundPots == 0: