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Hi, Michael. First off, you should spec a 12V relay that's made to handle inductive loads (you can see a HP rating). This type of relay has contacts which open more quickly, and are farther apart when open. A small standard relay might not even open up far enough to stop an inductive arc at line voltage.
Next, when using a relay to drive a relay, you have to be aware of the delay-on-make, which can be several milliseconds, especially for larger relays. That might help explain some of the curious results you're getting. Turn-on delay can be affected by wear and aging. It also varies from unit to unit, even in relays with the same part and lot number. Trying to get this kind of timing accuracy might be the wrong way to go.
It might be better to take a look at suppressing the arc, which you've already started to do. Here's an intuitive way to start. First off, remember your basic goal: you want the voltage across the contacts to rise just slowly enough so the contacts can pull away without sustaining an arc. That's all.
Remove the cover from the driving relay so you can see the contacts. Next, find the current rating of those contacts, and use Ohm's law to find a resistor which will result in about half that current.
For example, if you have a 220VAC load, and your relay can handle
10A,:R =3D 220V / 5A =3D 44 ohms
Choose a 47 ohm, 1 watt resistor here (carbon comp is best). Now get a selection of self-healing AC line-rated capacitors, and switch the inductive load with the 47 ohm and C snubber directly across the load, repeating and increasing the cap value until the contact arcing disappears, or at least is minimized. Without knowing anything about your 220VAC relay, it sounds like your 0.027uF cap might be on the small side.
Note that ITW Paktron makes a series of Quencharc snubbers that you can just plug in, which makes selection a snap. They're one-piece, epoxy-encapsulated units, and are very easy to use.
If all else fails, remember that physical distance is also helpful. Do what you can to place the arcing contact as far away as possible from sensitive circuitry.
Good luck Chris