Several people have had the same issue of not planning far enough ahead and actually having their visa before their travel date. What you are talking about is what they have been doing waiting in country until they get approval then border bounce to switch visas.
The risk is in the embassy wants you to come in for some reason you are SOL.
But since you are already in a different country it isn’t that much extra risk.
ETA has been pushed back. The digital TM7 arrival form is different. The TM6 was what was supposed to come back on May 1st, but no official details are out about it yet.
Worse case you will fill it out on your phone while waiting in line at immigration. But if you are this worried about filling out a form you might want yo rethink Thailand. They love to make statements that go nowhere and change the rules constantly.
Just relax and roll with the changes or you will stress yourself out of any enjoyment.
They aren't a business though. They work for the airport which is semi government owned and run. When has anything remotely government been worried about being efficient or making money.
Find a visa agent in the area you are visiting they will be able to explain everything. Maybe ask the same questions of several different agents as I have seen them give slightly different answers depending on what generates the most money for them.