All you need is the GPS coordinates for each control, so broadly you have two choices:
- Visit each one and store location using eg W3W
- Armchair plan using pins in Google Earth
Obviously the latter comes with various risks...
Always worth verifying the accuracy of locations by using CheckSites and visiting them "on the ground" before making the event live... I've never had an entirely correct armchair-planned MapRun course yet that didn't need at least one control tweaked
The controls were probably in the right place - although the distance from the control thingy was set too wide so it punched when you were nowhere near the feature which was confusing. No the problem was that one control was totally inaccessible.