210 is the normal operating temp for your 4.0L engine. I do not know of any vehicle that runs at 210 degrees F where the engine bay would not be too hot to touch in certain areas with your bare hands after it has been running a long time w/ the hood shut.
The only way to confirm your stock gage's reading is to install an additional, calibrated coolant temp sensor/gage, but I do not think that is necessary.
It's never a bad idea to flush and re-fill a cooling system on a used vehicle if you are not sure of the maintenance history, but based on your post, sounds like your Jeep cooling system is fine.
2002 Wrangler Sahara, all stock, 5-speed, Dana 44, dual tan tops, 2nd owner.
2008 Hemi Grand Cherokee Limited 4X4, Quadradrive II, original owner, 24,000 miles.