Are these @model classes correct for swiftdata with cloudkit?

I have used core data before via the model editor. This is the first time I'm using swift data and that too with CloudKit. Can you tell me if the following model classes are correct?

I have an expense which can have only one sub category which in turn belongs to a single category. Here are my classes...

//  Expense.swift
//  Pocket Expense Diary
//
//  Created by Neerav Kothari on 16/05/25.
//


import Foundation
import SwiftData

@Model
class Expense {
    
    @Attribute  var expenseDate: Date? = nil
    @Attribute  var expenseAmount: Double? = nil
    @Attribute  var expenseCategory: Category? = nil
    @Attribute  var expenseSubCategory: SubCategory? = nil
    
    var date: Date {
        get {
            return expenseDate ?? Date()
        }
        set {
            expenseDate = newValue
        }
    }
    var amount: Double{
        get {
            return expenseAmount ?? 0.0
        }
        set {
            expenseAmount = newValue
        }
    }
    var category: Category{
        get {
            return expenseCategory ?? Category.init(name: "", icon: "")
        }
        set {
            expenseCategory = newValue
        }
    }
    var subCategory: SubCategory{
        get {
            return expenseSubCategory ?? SubCategory.init(name: "", icon: "")
        }
        set {
            expenseSubCategory = newValue
        }
    }

    
    init(date: Date, amount: Double, category: Category, subCategory: SubCategory) {
        self.date = date
        self.amount = amount
        self.category = category
        self.subCategory = subCategory
    }
}

//
//  Category.swift
//  Pocket Expense Diary
//
//  Created by Neerav Kothari on 16/05/25.
//


import Foundation
import SwiftData

@Model
class Category {
    
    @Attribute var categoryName: String? = nil
    @Attribute  var categoryIcon: String? = nil
    
    var name: String {
        get {
            return categoryName ?? ""
        }
        set {
            categoryName = newValue
        }
    }
    var icon: String {
        get {
            return categoryIcon ?? ""
        }
        set {
            categoryIcon = newValue
        }
    }
    @Relationship(inverse: \Expense.expenseCategory) var expenses: [Expense]? = []

    init(name: String, icon: String) {
        self.name = name
        self.icon = icon
    }

}

//  SubCategory.swift
//  Pocket Expense Diary
//
//  Created by Neerav Kothari on 16/05/25.
//


import Foundation
import SwiftData

@Model
class SubCategory {
    
    @Attribute  var subCategoryName: String? = nil
    @Attribute  var subCategoryIcon: String? = nil
    
    var name: String {
        get {
            return subCategoryName ?? ""
        }
        set {
            subCategoryName = newValue
        }
    }
    var icon: String {
        get {
            return subCategoryIcon ?? ""
        }
        set {
            subCategoryIcon = newValue
        }
    }
    @Relationship(inverse: \Expense.expenseSubCategory) var expenses: [Expense]? = []

    init(name: String, icon: String) {
        self.name = name
        self.icon = icon
    }
    
    
}

The reason why I have wrappers is the let the existing code (before CloudKit was integrated), work.

In future versions I plan to query expenses even via category or sub category. I particularly doubt for the relationship i have set. should there be one from category to subcategory as well?