I'm not sure we need an options array for this, let's pass a map directly.
The map should be locale-sensitive and the current map should be used only with an English locale IMHO.

Wow, I like this feature.

But what if the$locale isfr and I use the default$charsReplacement = ['en' => ['@' => 'at', '&' => 'and']]. Then nothing will be slugged, right?

Does it make sense to be more complex here? Maybe dedicate this replacement thing to a separate class?

This should be a constructor argument, not a method argument. The argument should default to null and the default value be set on the property I think.

But what if the $locale is fr and I use the default $charsReplacement = ['en' => ['@' => 'at', '&' => 'and']]. Then nothing will be slugged, right?

Yes, that's the expected behavior to me.

Does it make sense to be more complex here? Maybe dedicate this replacement thing to a separate class?

Getting more complex is always possible by implementing SluggerInterface. Since theAsciiSlugger already does these simple mappings, I think it makes sense to make the map locale-aware (as the class already is).

I fixed my last comments. About the idea to use a translator, or how this could be leveraged from framework-bundle, we don't have to decide now. Let's wait for someone interested in resolving these challenges. Good as is on my side.

Thank you