Hello, we've tested Ironman compatibility from 1.13 to 1.14 and what we've found is that Cloud Saves will have issues (will not start, crash etc.)
While Locally saved Ironman games may work with no major issues* with loading.
When it comes to achievements _if_ you manage to get your 1.13 game to load in 1.14, you should be eligible for all 1.13 achievements you were previously eligible for, but no 1.14 achievements.
*Your mileage may vary as the game is complex and a LOT of things that we cannot foresee can go wrong.