Only way to get faster is to practice as far as I know…as the experienced scripters on here can churn out scripts fairly quickly. However this also depends on if they are just doing an simplified script or doing more fancy work especially with multi-axis.
For example Falafel spent 2+ Days of time on this script: https://discuss.eroscripts.com/t/najar-toru-2-multi-axis/158284?u=ratattack15
Which is unusual since they can get them out in 2-ish hours if you look at their two timelapse topics here: Scripting Timelapse - Me Speedrunning A RIM Animation and here: Scripting Timelapse - Dehya by Haruya . Which as you’ll be able to see what they used and did to make those specific scripts so fast.
So only practice helps cut down the time after a point since there is extensions for OFS that help like Util - Another Extension for OpenFunScripter and (multi axis helper) OFS Simulator3D Mod: Surge & Sway Fix - v1.6 .
There is tools that can help once proficient with getting a baseline script done so you can refine it and make it proper like: PythonDancer - A port of FunscriptDancer to Python , How to use FunscriptToolBox MotionVectors Plugin in OpenFunscripter and How to make script with Motion Tracking Funscript Generator .