ASW – Alternative hero leveling.

And even with the arrow upgrade, they will still be uncontrollable. But if the catapult is buffed, the choice regarding the OS might shift.

The problem is that after upgrading the fast units, there is almost no choice left. If without the arrow upgrade, it's either Machine Mastery or OS. Few will want to invest in a rare catapult. But if the catapult is the only available perk at level 2, the player will choose between quickly upgrading the catapult or a more complex option – OS / Machine Mastery.
Although additional scripted bonuses for the catapult will still need to be added.

Added 3 minutes ago

Your option:
Luck1 - Soldier - Wide Gates
Gates1 - Hellfire - Gates2
--- Total 3 skills and 3 abilities

My option:
Luck1 - Wide Gates
Gates1 - Hellfire
--- Total 2 skills and 2 abilities

This is if you tie Gates as a level 2 perk. But it can also be tied as a level 1 perk.

Added 8 minutes ago
My option with a level 2 perk without Soldier, i.e.:
Luck1
Gates1 - Fire - Gates2 - Lucky Gates

That is, it requires only 1 more perk.

Plus, you provided an example that is convenient for you (it won't always be like that, but only when the racial perk directly depends on the basic skill without intermediary perks). So the real advantage in speed is 0.5 perks.

Added 6 minutes ago

Moreover, the ideal option is 1 racial skill and 1 non-racial skill without perks, but this is technically impossible, although, if you try....

Why is this impossible? It's a standard case: a level 1 racial perk that depends on the basic skill. This is the minimum requirement. Is there a restriction on the number of level 1 perks in a racial tree anywhere?

Added 49 minutes ago
By the way, what I liked about RPE is that heroes are not required to have a racial skill at the start, and you can get more variety due to the use of 3 different perks instead of 2 + the standard racial one. Regarding the exe – I understand that it is only needed for compatibility with NCF. At least the RPE core works perfectly for me even with the old (unchanged) exe.