mongodb compass not using my index for querying

Question

Hi i am creating index using

db.commerceProduct.createIndex({description : "text"},  {"language_override" : "none", "name" : "test"})

Dataset has about 100K records.

I have two questions:

the description field is not null and neither an empty string. It gives me the following error on using following line in code:

db.commerceProduct.createIndex({description : "text"})

Error : :: caused by :: found language override field in document with non-string type.

I am not able to get why is it so.

Secondly when I make the following query in mongodb compass explain section: It does not uses the index that i created using the first command, to find it.

Query :

{"description" : { $regex: 'Cleanser', $options: 'i' }}

I am not able to understand why it does not uses the created index, Is there any way I can force it ?

Lastly I am trying to optimise the regex query for about 5 fields. I would be thankful if someone can guide me how to do so.

In short it takes about 700ms to do so, which i need to get below 500ms. I am thinking about compound indexing for now to do so. Any other methods are welcomed.

Thank you, have a good day.