The possibility of a time error is very very low.
The message you see is saying “When Minecraft checked the time jumped foward compared to last tick. Either the minecraft server has been stuck for a significant amount of time (long time between checks), or the server time changed forwards”
The server time changing forwards without your knowledge is extremely unlikely, and if it did happen, wouldn’t happen too often.
Which leaves the other possibility, the Minecraft server is pausing for too long between checks sometimes.
A common source of this problem is Java GC/Garbage Collection. Java needs to pause the server for a short time in order to clean up garbage in memory that is no longer needed. This takes longer the more ram you have.
The garbage collector needs to be tuned for different applications, at the moment, “screen -dmS mcmodded java -Xmx20g -Xms20g -jar forge-1.10.2-18.104.22.1681-universal.jar” isn’t passing it the arguments needed to tune the garbage collection for realtime game work.
@Aikar invented the timings system that created the report you showed, he is very knowledgeable in tuning the Garbage Collection for Minecraft.
As per my previous post, Please read his suggestions and implement them.