We have reviewed the availability of custom levels in the mobile version and have concluded that it is not feasible for the following reasons.
Store policies prohibit the use of content that has not been created by or licensed to developers.
We want everyone to use the level editor in good faith, but some bad actors may abuse this feature with offensive content.
To combat harmful UGC, the store requires developers to review UGC. However, due to practical limitations, it's not possible to moderate all UGC.
For more detailed store policies, you can visit the following websites.
App Review Guidelines - Apple Developer
As a result, we decided that the level editor would be difficult to port to mobile. We’ll continue to bring the mobile version with our original content.