Non Financial account type Avg on QTD/YTD

You are correct in that the "Non Financial" account type behaves the same as the "Balance" account type, meaning both do not translate and both have the same YTD as Periodic and QTD values.  They are balances or point-in-time.

For Non Financial or Balance accounts you can use the V# members to pull Month Avg, Quarter Avg, etc. as shown below.

But I suspect what you really want is for that account to have Periodic and YTD values which are different.  For that, you would want to use account type of "Flow".  This is also shown below.  Flow will behave like Revenue or Expense account types except not translate.

Here is the Design & Reference Guide info on account type behavior:

Account Type: Determines how the accounts roll up to a parent. Choose from the following options:

• Group: Setting used to make the account organizational-only and will not aggregate data.
• Revenue: Setting used to tag income accounts with a revenue attribute. 
• Expense: Setting used to tag expense accounts with an expense attribute. The amount entered does not have to be negative because of this attribute.
• Asset: Setting used to tag asset accounts.
• Liability: Setting used to tag liability accounts. The amount entered does not have to be negative because of this attribute.
• NOTE: Equity accounts should set Account Type equal to Liability because an equity account type does not exist in OneStream.
• Flow: Setting to hold values that act like an income statement account and have a periodic and year-to-date value. This account does not translate.
• Balance: Setting to hold values that act like a balance sheet account that are at a particular time. This account does not translate.
• BalanceRecurring: Setting for a balance sheet account that does not change over time such as an opening balance. This account does not translate.
• NonFinancial: Setting for informational accounts and not financial such as headcount or square footage. This type is used for legacy purposes such as upgrading from older systems. This account does not translate.
• NOTE: NonFinancial and balance account types are both available for legacy purposes. However, a NonFinancial data cell is not impacted by the flow member’s Switch Type property setting. See Switch Type.
• DynamicCalc: An account that calculates on the fly and does not need other formulas to run in order to calculate. 
• Example: Ratios that can be calculated as needed.