The organizational symbols used predominantly throughout this site are NATO military organization symbols, with some US Army WWII symbols added where necessary -- such as for the coastal artillery, horsed cavalry, antiaircraft (as opposed to air defense), machine gun, etc. units, as well as the movement modifiers underneath (motorized, halftrack, etc.).
NATO symbols are not completely rigid, and can be modified to suit need. As long as they conform to the basic system, there are no problems. In any case, just to be on the safe side, such non-standard modified symbols should be explained somewhere on the chart.
If the military symbols include words or abbreviations, the language can be native to the country being depicted. Again, an explanation or translation of symbols whose meaning may cause doubt should be provided in an accompanying legend.
One problem is that NATO assumes everything is mechanized, whereas the great majority of World War II units were usually on foot, and/or towed by horses.
Another problem is that NATO symbols change over the years.
A third problem is that my symbols are very small.
I have used US Army [FM 21-30] and Bundeswehr [zDv 1/11] manuals dealing with the symbols as agreed with in Standardization Agreement (STANAG ) No. 2019, 2nd Edition, (the NATO agreement which fixes the symbols). However, over the years, the various NATO countries have added their own symbols. (The Bundeswehr, of course, has felt the need to add hundreds of symbols that are NOT in accordance with STANAG, thereby, I feel, needlessly complicating the system).
Rather than use such an elaborate system to detail exactly what a unit is, I have stayed at a simpler level, if for no other reason than that my symbols are very small, and legibility would suffer if I added all the modifiers. In some cases, I have even created my own symbols because the NATO symbols do not exist or would be unclear at my small scale, (e.g., labor, fortress, medical, security, assault gun, flame tank, etc.). However, anyone familiar with the NATO symbols should be able to read the charts with only an occasional glance at my Military Organization Symbols Key.