solve several prestashop issues

Hello, I need some help with a prestashop website. The website has a custom template. The site has the following issues: - Admin sometimes shows 504 Gateway Timeout and is sometimes quite slow. After disabling 4 modules it showed less, when re-enable those modules it will show all the time. - The crypto payment modules seem to have a layout issue, this needs to be fixed. - The crypto payment modules not seem to be detecting the payment correctly this need to be fixed. I would expect to be fixed in a way that the complete order process is working, like payment is done and the order is in the system and emailed (I have email plugin configured for this). Not more than 4 items can be ordered, this is limited inside the cart already and on the product page can not be selected more than 4. However there is still 1 flaw in the system, if the shipping card already has 2 items and you try to add 3 then it says "succesfully added" while it does not add them. Instead of succesfully added it should display the error message which it also displays in the shipping card if there are more than 4 items.