Here is a previous post about it with some more points of consideration - Is it a "Natural language" form a good practice?
Can be very hard to deal with the lot of culture and languages.
Harder to design help and error message
It's hard to represent optional inputs, because it leads to empty sentences
Can be hard to parse fast by the user
Not good when it is more than a few field
Require to have fields a minimum related to be put in the same paragraph
Some research about it - https://www.jroehm.com/2014/01/26/ui-pattern-natural-language-form/
The consensus seems to be better conversion rates and appropriate for short queries as a fun and intuitive way to fill a form.
In experience, this makes sense since filling words in a long paragraph quickly becomes tedious and annoying (reminds me of some primary school low effort tests) vs filling a short sentence.
The cons start to add up when considering having to craft a paragraph to fit all the fields while giving the user a much longer task to complete a form (think about all the form best practices it breaks).
In your case, it seems you can use natural language forms for a quick initial trip query (there are many examples of this in the second link above) while pushing all other fields as filter options in the search results page.
There are 3 concepts working separately here (1) Initial Search (2) Advanced Search and (3) Filter and Sort. Natural language forms is helpful in (1), and becomes counter productive in (2) and (3). Keep these 3 concepts separate in the UI, as users are familiar with them.