Short answer. Yes. The rule lists an order or judgment that settles the account of an executor, administrator, trustee or guardian among those an interested person may appeal in special proceedings. You need not wait for the settlement to conclude before bringing the appeal.
What the law says
Settles the account of an executor, administrator, trustee or guardian
Rule 109, Section 1 — Orders or judgments from which appeals may be taken. Read the full provision →
A short clause with a wide reach
The listed ground names four fiduciaries in one line: an executor, an administrator, a trustee and a guardian. So this is not a rule about estates alone. An order settling the account of a guardian over a ward's property, or of a trustee, falls in the same category as one settling an estate administrator's account. If you are an interested person in any of those proceedings, the settlement of the account is an order the rule treats as appealable.
Why accounts are appealable when made
An accounting is where the money is actually decided — what came in, what was spent, what is left to distribute. Once approved, it becomes the basis on which everything downstream proceeds. Deferring any challenge to the end of the proceeding would mean the distribution is worked out from figures nobody could test at the time they were fixed, and by then the assets may already have moved. Listing it here keeps the point reviewable while it can still make a difference, which is the same logic that makes a determination of heirship appealable when it is made rather than at the close of the case.
Who may bring the appeal
The rule opens by giving the right to an interested person, and that framing runs through all the listed grounds. It is not confined to a party who filed something. Heirs, and others whose entitlement depends on what the estate actually holds, are the people an accounting most directly affects. Whether you are an interested person for this purpose depends on your relationship to the proceeding, and it is the first thing to be clear about.
Look at the whole list before deciding
The same rule makes several other orders appealable, including one allowing or disallowing a will, one determining the lawful heirs or a distributive share, and one allowing or disallowing a claim against the estate or a claim presented on the estate's behalf in offset. It also excludes one thing expressly: no appeal is allowed from the appointment of a special administrator. If your objection to the accounting is part of a wider dissatisfaction with the administration, put the whole picture in front of a lawyer.