"This sentence" is an indexical term. An indexical is a term like "I", "today", or "this city" where the reference of the term depends on the context of the sentence--who said it, when it was said, etc. So for example, if Joe Biden were to say, "I am president of the United States", he would be uttering a true proposition, but if I were to utter the exact same sentence, I would be uttering a false proposition. The difference is in who utters the sentence, which is part of the context.
Indexicals have lots of strange properties. For example, the sentence "I am speaking", when spoken, seems to be necessarily true in some sense, but it doesn't seem to be a logical truth. This category of a necessarily true sentence that is not a logical truth is difficult to square with traditional ideas of logic.
What an indexical term refers to is not decided in the same way as for other types of noun phrases. Your question offers a clever example of this difference. If you translate, for example, "The singing man fell off the ladder" to French, you translate the definite description "the singing man" to French by producing a phrase with the same meaning, and the phrase then has the same referent (the thing that it refers to). For definite descriptions the meaning fixes the referent.
For indexicals like "This sentence", the meaning does not fix the referent. In the sentence "This sentence is written in English", the "this sentence" refers to the English version of the sentence. If, as you point out, you translate the meaning into French, the sentence becomes false, and the reason it becomes false is because the referent of "this sentence" is different in the French translation than it was in the English original.
So the answer to your question: yes, the sentence is meaningful, but it doesn't have the simple mapping from meaning to referent that most sentences have.
As to whether you can have a consistent language where a sentence can refer to its own meaning: yes, you can, but you have to be careful how you do it. Indexicals in general are a common source of trouble.