Again, an improvement but far from ideal.
The relay coil requires ~38mA to operate which is more than I would pass through a PC817. They are intended to be used in feedback applications where the LED current can control conduction through the output transistor rather than as power switches. Besides, the relay itself can withstand up to 1.5KV so why use an additional isolator and power it from an un-isolated power source.
The flood fill means that all the unused areas, at least the ones around the MCU are filled with copper and connected to ground. Ideally, you use a double sided board and make the top side all copper, including holes to ground points on the bottom but isolate places where other wires pass through holes. For most PCB manufacturing processes, the board starts as a copper surface and the gaps between tracks are etched away so the more you leave, the less you have to dissolve away. The flood fill technique lets you minimize etching and make the ground better at the same time. Lower resistance grounds always work better.
Your new design still doesn't deal with the crystal issue. The clock circuit consists of the crystal and two loading capacitors, C1 and C2. If noise gets injected into the oscillator path it can cause unpredictable operation or a complete crash. Try to minimize the wiring length between those components and the MCU and connect the capacitor grounds directly back to the MCU without touching anything else. It may mean running two tracks to the same pin on the MCU but it keeps currents on them apart from each other.
Overall, you are improving the design but I would suggest doing it this way:
1. start with the outline of the PCB.
2. locate places where adjustable components are accessible. For example don't mount side adjustable potentiometers where another component blocks access to the slot. Fix the position of adjustables, make them easy to reach, you can work on getting the tracks to meet them later.
3. Decide which components have to be kept together (Crystal, C1, C2 for example) and which should be spaced apart. (relays, high voltages for example)
4. Leave space for decoupling capacitors close to the MCU supply pins.
5. Make sure current paths are sensible. Remember that even short tracks drop voltage along their length when current flows through them so try not to make any track share currents that might change during operation as it could result in varying voltages where you don't expect it.
There was a classic error of type 5 in the original PCB design where the relay currents passed along long tracks and the MCU supply was taken from along the track length. It meant the MCU supply voltage went up and down according to how many relays were operating. Usually, the best place to draw current from is the output pin of the voltage regulator or the capacitor across it's output.
Brian.