So the default MySQL in SME server has EOL in 2013
Nope. You need to really read this stuff carefully and not jump to assumptions. It isn't quite so simple, and this has been explained here a number of times before.
SME is unusual because RHEL are unusual, and SME follows RHEL. The installed versions are supported by RHEL for life of the OS.
So both the *installed* versions of PHP 5.3.X and MySql 5.1.x are supported by Redhat until RHEL 6 goes EOL.
The fact that application may want a newer version does not change the fact they are still supported. But ONLY those versions.
The SCL versions are supported too, but ONLY for whatever the current versions of PHP are so currently PHP 7.2+
That isn't our fault. It's an upstream choice (and prior to SCL you had to take risks with various different builds of PHP)
RHEL chooses longevity & stability over latest & flakiest. I believe they supply quite a few places with strict compliance requirements so new stuff is tested over months before being released. Think say spys & other government orgs, banks etc.
They want it hardened, not the newest stuff on the block.
If you want cutting edge then use another distro.
As it is your near 10 year old OS can still run PHP 7.3 and MySql 5.7 and Maria db.
As to your original question I don't know right now. I have one of a nearly 500mb I restore for testing in mysql 5.5 and it is fine with stock settings.
You don't actually know which bit is failing right now. You refer to mysql57 telling you but provide no evidence of that.
What do your logs tell you?
Why don't you just import in the command line?
Something like:
mysql57 -u root mydatabase < daily_database_backup.sql
That may tell us a bit more.