The voltages are fine in your HWMonitor are fine and safe. You could probably reduce the VCCIO and VCSSA closer to 1.0V. If experiencing any instability, raise your voltage on these two back up. As they are, the voltage is fine and it shouldn't be causing instability. These could also be increased as much as 1.2V without any issues, some run more. Running a lot of voltage on this can degrade your memory controller. I actually run mine at 1.05V even with much faster memory but every CPU, mobo, and ram kit is different.
Vcore could be higher without any issue and may resolve instability, load voltage of 1.2 is typical. There is no point in having it higher than necessary, however. You could bump it a tiny bit to 1.21V etc if you crash at all, see if it crashes again. If it does, you can bump it again. VDimm can be raised if needed, you could bump it a bit, a lot of kits run at 1.35V so you have headroom to bump it higher, could bump it to 1.205, 1.21, etc increments if you are still unstable. That doesn't mean your kit needs it though. Your temperatures are perfect.
I will do my best to explain some of the voltage options as I understand them. I may be wrong on these points, TPU users feel to correct me.
For a setting that can change, my understanding is that Asus has several voltage modes: Auto, Adaptive, Manual, and Offset.
1) Auto is the default Intel specified VID (the voltage for a given clock unique to this CPU) chart. The motherboard will attempt to deliver something near VID at any given clock. This may actually vary quite a bit above or below from the VID.
2) Adaptive will run at stock voltage VID until it is in turbo load and then it will run at the adaptive setting. It counteracts some of the issues with undervolting using offset, see #4.
3) Manual will run at a fixed voltage at all times which offers less power saving but offers more stability. High manual voltages may degrade silicon faster.
4) Offset will run at VID +/- the offset variable. A large negative offset does not work well for CPUs that can undervolt well at Turbo speeds because you may experience too low a voltage when at power saving low clocks. Attempts to balance this can be made with load line calibration. Conversely, a large positive offset can result in more voltage than is necessary for low power states. Instability can also occur when switching between idle and load or from AVX to non AVX states as it moves up and down the VID chart. Load line calibration can help with this but can also result in too much voltage being applied during voltage overshoots.
Additionally you should understand Load Line Calibration or LLC.
I am not sure what LLC options are available, I looked as the Asus ROG Maximus XI Hero WiFi manual and didn't see what options you can select. Some manufacturers use terms such as Low, Medium, High, Very High and some use numbers. Some use numbers where the larger number is more LLC and others use numbers where the larger number is actually less LLC.
Generally the way this works is when a processor switches from idle to load, the VCore voltage droops once the CPU is in load state. When exiting load state back to idle, the Voltage will briefly rise. Running higher LLC reduces the VDROOP by providing extra compensating voltage to counteract the droop. However, there is a downside to LLC and that is that when running a very high LLC setting, voltage will overshoot periodically during the load to idle when voltage rises, over time this process could cause degradation of the CPU. These overshoots are difficult to measure with PC monitoring software. As a general rule, running more LLC will result in more load voltage. It may be that when you changed your bios settings, LLC changed.
der8auer explains it well here: