If you have a syntax error in an impossible place, the project is corrupt in some way. File a feedback case and attach the project so that Xojo can fix the issue for everyone. It might be best to include the original un-Xojo’d project as well.
if the problem is in application name, you must try to change some field in the shared (or mac or win) properties, then compile, then revert back and most of the times it works. it may not be the field I moved that will be the same as yours.
The only fast way to get a whole project updated is to hire a professional who can. If you’d rather do it yourself, the community will help you through the process by answering specific questions. But a general “how to” is very specific to how your old stuff was implemented.
Beware of shortcuts. Shortcuts are how you make more suffering for yourself. Every time I see someone take a shortcut when presented the correct way to do something, they are back with problems very quickly.
You will discover that a lot of things that just “worked” in Carbon-based apps become very painful to deal with when you just hop over to Cocoa and 64 bit. Your app’s UI responsiveness gets tanked when you have long running background loops. If you used threads, you’ll run into the inevitable issues presented by “ThreadAccessUI” exceptions, even if just reading a UI control’s property.
One option that I would recommend is looking at 2016r3.3 as the “mediator” for moving your code from the old world to the modern Xojo environments. That is where I found the best balance between being able to at least debug/test my old projects so that they worked in the newer Xojo world.