Hi Luis,
I'm chaining an startech USB-C/TB3 to TB2 adapter + Apple TB2 to Firewire 800 adapter to connect my Intel NUC to my Paca and this configuration works very well.
I understand you have a Mac but I believe my Windows config should also work for the mac.
So my suggestion is to try both USB-C/TB3 to TB2 + TB2 to Firewire 800 APPLE adapers first.
And if that doesn't work, then return the Apple USB-C/TB3 to TB2 adapter and swap it for the Startech instead.
Best,
eli