Is there any doubt concerning working for a company that relies for its maintenance on the proceeds of a maintenance deposit placed in a bank, where the unit's share of expenses and returns are calculated and compared?

There is no harm in deducting an amount from the property owners for maintenance and investing it in a permissible way to benefit from its profits for that purpose. If the money is deposited in a bank that regulates its transactions according to Sharia (definition), then there is no harm for you in performing the accounting, recording, and reconciliation; because it is assistance in what is permissible. However, if the money is deposited in a usurious bank, then this is a prohibited investment, and it is not permissible for you to work on accounting for this investment, writing it down, and reconciling its interest, because that is from writing down usury. The Prophet, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, the one who writes it down, and its two witnesses. The one who writes down usury includes whoever drafts it, records it, reviews it, and everyone connected to it.