I'm aiming to simplify the I/O setup for the machine, anyone see any issues with my planned I/O board? Pneumatics are all run off 24v switches and the board can only output 5v, hence the relays.

Does anyone see any mistakes or issues?

If you do not need galvanic isolation, you can use logic level MOSFETs instead of relays.

Big thoughts that I vaguely understand and had to read up on a bit to figure out.

So firstly, and I mean this, thanks. Read and thought a bit to make sure I was following your words as I didn't quite catch it initially. Any time I learn something new is a good time.

I was thinking the system does need galvanic isolation as my 5v ground is from a different supply than my 24v ground.

Here is a simpler version of the output.
These MOSFET solid state relays can drive your relays directly. Max rating is 60V, 500mA although I would only use them at about half that. By the way, they can also switch AC.
There is a resistor in series with the inputs to set the current.
Indicator LEDs run on 24 VDC as do the relays. I drew them as 24 VDC since that's the supply in your diagram. The circuit could be used for 12 VDC if you prefer.
Diodes across the relays to catch the turn off spike that might harm the MOSFETS.

Here is a simpler version of the output.
These MOSFET solid state relays can drive your relays directly. Max rating is 60V, 500mA although I would only use them at about half that. By the way, they can also switch AC.
There is a resistor in series with the inputs to set the current.
Indicator LEDs run on 24 VDC as do the relays. I drew them as 24 VDC since that's the supply in your diagram. The circuit could be used for 12 VDC if you prefer.
Diodes across the relays to catch the turn off spike that might harm the MOSFETS.

I've kind of sold myself on the optocouplers and got parts on order now.
Is there a reason to prefer MOSFETS over optocouplers?

The MOSFET SSRs can handle more current and voltage than the typical optocoupler and eliminate the need for an intermediate driver. For low power they're equivalent to a relay contact.
If your circuit didn't use both an NO and NC contact they could have replaced the relays too.

The MOSFET SSRs can handle more current and voltage than the typical optocoupler and eliminate the need for an intermediate driver. For low power they're equivalent to a relay contact.
If your circuit didn't use both an NO and NC contact they could have replaced the relays too.

Ah, that makes sense. I wanted the relays to swing both ways for future expansion purposes too.

You can always put relays behind SSRs.

Caution... many SSRs are A/C only output and would not work to drive 24 VDC relay coils.

The TLP222AF can handle AC or DC. The 60 volt rating is more than enough for a 24V circuit. I would keep the current under 200 mA to keep the heat down. 200 mA is not a limiting factor as the coil current of a small signal relay is usually under 50 mA.
They are packaged in a 4 pin DIP like the typical opto coupler and cost only a bit more, $1.09 from Digi-Key.