"reservation regarding" is correct and usable in written English.
You can use it to express doubt, uncertainty, or hesitation about something. For example, "I had a reservation regarding the instructions given by the teacher."
And I have some reservation regarding whether a democratic system is what China needs right now.
He expresses reservation regarding the existence of religious cosmopolitanism within a household where family members followed multiple faiths.
The next step happens on May 3, when the EPA holds a public hearing on the Moapa reservation regarding a pollution permit for Reid Gardner.
In addition, we had some reservation regarding arrival by ambulance as a component of any rule.
He was an active person before, during, and after intervention, but expressed a slight reservation regarding activity level after intervention.
I would, however, want to express a reservation regarding the boundless possibilities the information society has to offer.
One reservation regards as to whether there is a direct link or merely indirect links via for example lifestyle, which correlates with education.
In turn, "the Lady" was generous to agree to contest elections despite her reservations regarding the 2008 Constitution.
I'd had reservations regarding HRT, having read plenty about its link to the increased risk of breast cancer.
One of Uruguay's foremost artists, singer-songwriter Fernando Cabrera, 57, has his own reservations regarding legal marijuana.
Do you think China¿s talks with Russia about gas supply have anything in common with possible Chinese reservations regarding nuclear power?
