After being declined by Grammarly, Microsoft Word and other grammar/spelling tools, I'm quite skeptical to use the adjective word 'vacational' i.e. related to 'vacations' — free/leisure time.
I have been using it for past many years and did not bother much about it. Why? Because I was (or am?) confident.
In fact, in Berkshire, UK there's a school (accredited by the British Council) titled:
Vacational Studies English Language Summer School
The school is very old and in the market for 42 years. In fact, it's an English Language learning school!
and they run a course:
Vacational Studies English Language Summer Course
We all know that the language of English adapts things very quickly. Do native speakers prefer this? Do they mind this word if written somewhere?
Edit after reading Catija's answer:
I gave one example that I found it easily. But I think considering 'vacational' in the sentences and not just in title as the answer says is also found.
Here are some of the examples:
So much so the Hollywood star recently mused, "I don't think you find them, I think they find you" about landing a keeper instead of a vacational lover.
Azel Prather Jr turned to a popular funding website GoFundMe to pay for the round trip flight after his girlfriend Marissa planned a holiday to the popular location during the vacational period.
Because, as a good friend told them recently, when in search of a vacational playground, look no further than the Hamptons…the Rocky Hamptons.
Regal Financial and Development Corporation. This San Francisco-based company envisions a mix of projects, including a vacational college for healthcare industry jobs and a warehouse facility for food and wine export to China.