Could someone explain why the build is failing?

Nothing related to your patch. But there are some cs issues and I am not sure you chose the best solution.
Will look tomorrow.

I don't think we should do it as you propose. See #27823 (comment)

Your patch gives

Mine gives

As you can see, the text is placed OK, similar to LTR and not near to the icon

This is a .diff I made here:

diff --git a/administrator/templates/atum/scss/blocks/_modals.scss b/administrator/templates/atum/scss/blocks/_modals.scss
index 4975528..8246c79 100644
--- a/administrator/templates/atum/scss/blocks/_modals.scss
+++ b/administrator/templates/atum/scss/blocks/_modals.scss
@@ -66,5 +66,4 @@
     background-color: var(--danger);
     color: hsla(0, 0%, 100%, .9);
-
     display: inline-block;
     width: 2.375rem;
@@ -72,4 +71,8 @@
     margin: 0 16px 0 -22px;
     line-height: 2.375rem;
+
+    [dir=rtl] & {
+       margin: 0 -22px 0 16px;
+    }
   }
 
@@ -81,5 +84,4 @@
     background-color: var(--success);
     color: hsla(0, 0%, 100%, .9);
-
     display: inline-block;
     width: 2.375rem;
@@ -87,6 +89,9 @@
     margin: 0 16px 0 -22px;
     line-height: 2.375rem;
-  }
 
+    [dir=rtl] & {
+       margin: 0 -22px 0 16px;
+    }
+  }
 }

The whole file would be
_modals.scss.zip

Could you correct this PR, or shall we close it and I will make a new one?

@infograf768 I will correct this PR

I have tested this item ✅ successfully on 288ec4e

thanks.

I have tested this item ✅ successfully on 288ec4e

RTC

thanks