g00d

Well, I made some progression and want to share it with the community:
 
Related to question 1)
still unresolved because I don't know if I am missing something or this could possibly be a bug?
 
Related to question 2)
the culprit lies inside the function storage_info() because I am not using simply /dev/sda1 but an encrypted drive. My disk *is* /dev/sda1 but it's LUKS encrypted and so my device for the system is /dev/mapper/rootfs or even more /dev/mapper/volumeGroup1-rootfs because I am also using LVM. The storage_info() function does not take this into account. I had to modify the function to this here:
function storage_info() {         # storage info         RootInfo=$(df -h /)         root_usage=$(awk '/\// {print $(NF-1)}' <<<${RootInfo} | sed 's/%//g')         root_total=$(awk '/\// {print $(NF-4)}' <<<${RootInfo})         StorageInfo=$(df -h $STORAGE 2>/dev/null | grep $STORAGE)         #if [[ -n "${StorageInfo}" && ${RootInfo} != *$STORAGE* ]]; then         if [[ -n "${StorageInfo}" ]]; then                 storage_usage=$(awk '/\// {print $(NF-1)}' <<<${StorageInfo} | sed 's/%//g')                 storage_total=$(awk '/\// {print $(NF-4)}' <<<${StorageInfo})                 if [[ -n "$(command -v smartctl)" ]]; then                         #DISK="${STORAGE::-1}"                         storage_temp+=$(smartctl -l scttempsts $DISK 2> /dev/null | grep -i 'Current Temperature:' | awk '{print $(NF-1)}')                         storage_pwroff_retract_count=$(smartctl -a $DISK | grep Power-Off_Retract | awk '{print $10}')                 fi         fi } # storage_info  
in detail:
 
it needs to comment out the originally line
#if [[ -n "${StorageInfo}" && ${RootInfo} != *$STORAGE* ]]; then  
and change it to:
if [[ -n "${StorageInfo}" ]]; then  
it needs to comment the following line here inside the if clause:
#DISK="${STORAGE::-1}"  
and it needs a definition in the top of the script where we need to add a DISK variable. Simply said, we need to separate DISK and STORAGE in case of encrypted systems and/or LVM used. The top of the script 30-armbian-sysinfo looks like that in my case:
DISK=/dev/sda1 STORAGE=/dev/mapper/volumeGroup1-rootfs  
that way the script works fine and outputs the correct values.
 
Related to question 3)
solved also according to question 2. I added the threshold 50 for the power-off retract count in the beginning for the script:
[...] CPU_TEMP_OFFSET=0 HDD_TEMP_LIMIT=60 PWROFF_WARN=25 [...]  
The variable and display command should look like that:
disk_pwroff_retract_count=$(smartctl -a $DISK | grep Power-Off_Retract | awk '{print $10}') [...] # display info display "HDD PWRoff Retract Count" "$disk_pwroff_retract_count" $PWROFF_WARN "0" "times" "" ; a=$((a+$?)) [...]  

Me again. I figured out what the problem was and I was able to solve this like that:
 
the original /boot structure contains three symbolic links, in my case on the ODROID-HC2 (which is equal to odroidxu4):
 
dtb -> dtb-5.4.151-odroidxu4
uInitrd -> uInitrd-5.4.151-odroidxu4
zImage -> vmlinuz-5.4.151-odroidxu4
 
The default boot.ini is seeking for that link names but on the fat system it's not possible to have symbolic links. I just renamed (or one can simply copy) the existing three files like that:
 
dtb-5.4.151-odroidxu4 ---to---> dtb
uInitrd-5.4.151-odroidxu4 ---to---> uInitrd
vmlinuz-5.4.151-odroidxu4 ---to---> zImage
 
I also found out that /boot folder is NOT being red by boot process, it looks at the root folder for those files. So I "mv /boot/* /" moved the complete content of the /boot folder into the root. That way the boot process works like a charm.
 
Thank you Igor for assistance. Have a nice weekend