Not necessarily. Depends what and why they are failing. They also won't be able to determine the amount of life left on the other 4 coils. Beyond cylinder issues, you still have all of the labor intensive parts that should have been replaced with the chain that need done. The fact that you are putting money into this car (paying for the labor/inspection) after all the advice and problems presented, just shows that you are sold on this car already. I suggest the next steps are a second job and becoming real familiar with the Gen 4 Maintenance & Troubleshooting section. Find a mechanic whose kids you want to put through school or invest in a great tool set.
I'm guessing the guy either had to pay for a motor ($3k-5k for a junkyard motor), labor (~20hrs), and all the needed maintenance of the replacement motor or he sold the car stupid cheap/scrapped it and lost a ton of money in the deal.
Yeah, look I have never done my timing chain and water pump, these are long and labor intensive processes. Even with a friend who owns a lift - I would still have a trusted shop do my work. All replies have been to help protect you financially. I can tell you this car is very costly when doing the type of work this seller is saying they are doing.
Attached is the bill I paid for just making sure my Accel coils - might - be causing a misfire just to rule them out. Look it hurts to dump nearly $500 on being proactive and getting ahead of a potential problem. This was for a stutter on a rolling wot spark bang dead pedal.
If you like me have a daily driver as a backup, and the financial means to throw parts at the problems- warm garage and like @Ta2dResqr the tools available- great, good for you. If this will be your daily driver and have tight money issues, for the love of anything wait and find another candidate.