I don't think you need to use bryntum.scheduler for your custom class. I guess it's your own class that you just imported, so use that name to create an instance
import SchedulerCustomTimeAxis from './folder/SchedulerCustomTimeAxis.js';
// ...
this.SchedulerCustomTimeAxis = new SchedulerCustomTimeAxis({
})
i can't do that :
import import Scheduler from '../../../lib/Scheduler/view/Scheduler.js';
import DateHelper from '../../../lib/Core/helper/DateHelper.js';
in my lwc