Not a native speaker of either French or English.

May be I am misunderstanding your question. Note that German, unlike English (both are Germanic languages), does not possess also a Simple Present Continuous.

To emphasize what one is doing right now, in English, we use the verb “to be” and the “present participle” of the verb :
I am doing (doing is the present participle of to do).

To translate the Present continuous in French we have two possibilities:

If someone says: Qu’est-ce que tu fais? (French Present Tense)
we understand that it is now, so if we reply: je mange, we understand, I am eating!

If you want to emphazise, you can say: Qu’est-ce que tu es est en train de faire? Je suis en train de manger!

https://www.leaflanguages.org/french-grammar-present-continuous-etre-en-train-de-infinitive/

https://www.frenchtoday.com/blog/french-verb-conjugation/french-mistakes-beware-verb-ing-constructions/

As a GENERAL matter, French has only a single present tense, unlike English.

That means the following:

Ils se cachent dans le jardin. can be:

They are hiding in the garden [now] OR They hide in the garden [when they play games].

I drink coffee. = Je bois du café. can be both drink and am drinking.

Here’s the trick:
être en train de faire quelque chose is, of course, translated into English using the present continuous but the inverse is not true: The English present continuous is simply not translated into French using en train de as a general manner.

• Ils sont en train de faire leurs devoirs. = They are doing their homework.

Forgetting translation for a moment, you have to see when être en train de might be used in French. It is used to emphasize an action occurring "right at the moment of speaking".

Q: Oú sont les enfants? Ils font leurs devoirs?
Ans: Oui, ils sont au salon, en train de faire leurs devoirs.

Now, the answer there could have been:
Ils sont au salon. Ils font leurs devoirs.

The use of en train de just emphasizes that the action is happening now and is less "harsh" than the simple present in this case. One has to develop a feeling about when to use it. It can also be used to avoid ambiguity that may arise.

Ans: Ils ont au salon mais ils ne fichent rien. Ils ne sont pas en train de faire leurs devoirs.