Messing with Event Manager filter

I am having problem in bookings in Event Manager. Customer get message they can′t book because not enough free spaces, but anyway, the booking is registered in eventmanager admin, which means overbooking appear and events get marked fully booked, even if customers are notified not enough spaces.
This text is from Event Manager support:

Hello, I’ve done some tests and the problem is coming from Anti-Spam by CleanTalk.

I’ve never come across that plugin, but I downloaded and did a quick search for the filter I know was getting switched, and they are messing with our filter, em_booking_validate and returning a true value even though it shouldn’t.

I’d have said it’s likely related to our new updates and how we change tickets, but then I’d have expected them to validate a different filter.

You can confirm this by checking the plugin I installed (our plugin actually), WP Safe Mode, check the settings and either enable it for the site, or add your IP and enable it just for you (you need site + IP if you’re going to submit as a guest). Currently, safe mode on disables only that plugin, and you’ll see it works.

As for the problem, I didn’t dive in that deep, but I’m guessing they validate spam via em_booking_validate and then return true if there’s no spam detected. That’s wrong, they should return either the param passed onto their hook, or empty($EM_Booking->errors). because maybe there’s no spam, but it doesn’t account for whether our booking form validated or not in the first place.

Our support contact at Event manager say you can communicate with him directly, however, I don′t want to share his contact detail here.