prescription from any other place other than Thailand is not accepted, let alone not in English . Prescription must be given out by a registered doctor , Swiss doctors are not registered in Thailand. It would be accepted on the airplane or if sending by post but can not use it to buy from local pharmacy . Local pharmacy normally says need prescription , what they mean is they can not sell it. Even if you had one from a local doctor, then they will tel you to visit hospital. Highly controlled medication is not sold to pharmacies and law has tightened a lot about 2 years ago. Before only pharmacies were punished for selling such meds, now suppliers are also punished. Also be advised depending on what meds you need, it may not be available at all if it is not Thai FDA approved , but doctors can often find similar meds. Unfortunately if it is prescribed only , generic will not be available so the cost would be fairly high
Thai system is different . Anything and everything sold at pharmacy does not require any prescription. If pharmacy do not sell what you need because it’s highly controlled then only option is seeing a doctor at a hospital who will prescribe and hospital pharmacy will issue it
Depending on what system or app landlord used, it can not be screen shot , there is no receipt number or anything. What you should do , just in case , also bring a letter from landlord confirming where you staying and confirming online was filled. Most of the time this is all that is needed