The implementation of this new form if im not wrong came out arround 4 or 5 months ago, all beginnings are hard, and excuse for those that can not right or read or are not good int tech will have to find out to get some help as is posible to fill it out ahead of time before your trip. Some countries as Canada started to get rid of the inmigration and custom form 2 years ago and placed kiosk where must be scanned your passport and use the touch screen to complete the process by yourself, not much diference and what you are doing here. Sometimes the problems that you mention can be caused for webpage bad conection, webpage do not work as should be, and maybe is your browser anything could be. Now arilines must send the link of the e-ticket with the information that must be fill it out when reservation is completed.
Now for sure goverment has better and faster statistics about people arriving and leaving, also exactly from where they are coming from, in the statistic there is a distortion on the flow of people comming with conecting flights, you get the form to enter here in the 2nd. leg of your flight (Panama) that you must write you are coming In a flight number and country that you are not coming because is a transit and as example of that is Panamá, Statistic says 500,000 people arrived from Panama in a year but Turism can not take any action about that because from thsoe 500,000 16,758 are really from there. The new form ask if you arrive in connecting flight and if you says yes then ask you the 1st leg of the flight from you are departuring, so no can be traced faster the flow of pax and base on that take decitions and where to make strong the promotion and see where is working better. Same thing is doing the new program One Mitur, they are also connected with Migration, Airlines for reservations and reservations from Hotels, now they do not have to wait to receive information from otheres, now they has it day by day.