Old info from rec.games.pinball: https://forums.tomshardware.com/threads/solid-state-relay-for-sys11.121618/
"This is fine for home games but do not use solid state relays on route
machines. I have experimented many times with using solid state relays
in pinball machines for various add-on devices, such as auxilary audio,
topper lighting, and other visual fun. Holloween is one occasion where
this is so much fun.

The problem with using solid state relays was demonstrated by Bally a
long time ago in the service school classes. The failure mode of these
devices was to usually short the output "on". This is really bad for
flash lamps. The plastic domes, sometimes called "hats" were not
designed for the temperature of a continuously running #89 lamp. (Ask
Premier about this one! The burn't down a few Monte Carlo's and Gold
Wings. I had one of each back then).

Bally used this type of feature for the neon on Strange Science. Since
a Neon doesn't have a heat problem, this application was OK.

There is an issue with inrush current on SS devices, and also a leakage
current. The first devices I used on this type of pinball application
I noticed a strange issue in low lighting. When the device was "off"
the filaments of the flashlamps were glowing very slightly due to
leakage current. A snubber circuit, (RC circuit), was used to keep
this at a minimum.

Triac's were usued with a high current rating for GI, because the way
they were made did not have this issue of shorting on. Since they
operate with the zero crossing feature they were never really "on" full
time. (In human terms, that is).

I believe P & B has a pretty nice line of SS relays but just a
suggestion do not use the small cube type. They can't handle much
current and some were even discontinued. I used the large block type
with no failures. The neat thing is a +3vdc to +32vdc volt gate can
control about anything. Even using the AC gen illumination line you
can add a couple of diodes and you have a gate source.

In fusing, you can experiment with slo-blo fuses and make your own
current curve. It takes a while to develope the exact curve for your
experiment, but it will only allow the lamps to remain "on" for a safe
duration of time in the event of relay failure, then the fuse will
blow.

Good luck and please don't burn up that Swords Of Fury! I love mine.

Mario
Pinthetic"

Keep in mind, the demonstration described would have been no more recent than 1999. The technology could have improved a lot since then.

Current games use flashers, are they solid state?