Maybe "Tidy Sum" is a bit 'dirt y'.
Original in French., but very good/ easy Firefox browser translation. If you want the web [WARNING] address for more info, PM me.
The author uses the term "cult", when referring to  SSP.
This is from 2012 AD web page, mostly, but as you notice, it has been updated 2018 AD. This is a 90 % Firefox translation, 10% adapted by me. Firefox did a good job with the text, but a sloppy job with the numbers, $$$, Euros etc., so I corrected most I hope.

STREETPRESS,
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Jade Serrano
Inheritances, Generous Benefactors and Transfers to Switzerland

27/11/2018 The Big "Tidy Sum" of the Tradi Cathos of the Fraternity of St. Pius-X
Suspicions of undisclosed cash wages, liquidities and forwarded $$ to Switzerland...Tradi Catholics uncatholic ways to top up their bank accounts.

BUT WHERE DOES THE MONEY GO?

The 2012 financial balance sheet provides some information on the use of the French cultural association with their money. EUR 1.073.913 was paid to the General House, domiciled in the canton of Zug, Switzerland. The French cultural association, like its other national structures present in Europe, must give back five percent of the donations from the various churches to the parent company, explain several sources (1). One of them even presents us with an e-mail that evokes this tithe. Asked by StreetPress, the Benelux District SSP acknowledges this practice, which it justifies.
...
Moreover, according to the 2012 Financial balance sheet, EUR 1.602,584 has been spent on rents for civil real estate companies based in Suresnes., (France) The Fraternity also reimbursed EUR 497,373 in mileage. But the BIGGEST item of expenditure in the Brotherhood remains the salaries and allowances: 1,620,799 euros paid to its employees. According to an accountant to whom we presented these docuмents, the THREE religious [individuals], agents of the association, for themselves only, would share the sum of EUR 390.219. [ED. about $400,000.00 USD 2012 AD.  I am wondering if these three are priests, abbot, getting compensated 133,333.00 each? Just asking...]

This would be the 'declared' part of this financial report. A former SSPX accountant in Belgium reveals the opacity of the accounts of the Fraternity.
...
Volunteers/ UNDER THE TABLE
[ED. neoSSP has a tendency to recruit volunteers. No work contract, only volunteering.]
Really? neoSSP: 'The volunteers...() are free to do as they please with their time. By definition, these persons are not paid, they are reimbursed for their expenses, if there are any.'

Georges, former accountant, says:
'For reasons re. social coverage (liability?), the teachers were often declared under an employment contract, as part-time. An equivalent of their total salary was given in cash. About 50% declared, 50% under the table.'
A woman, Miss G., provided services at an establishment for nine years plus. Looking for change, she went to the Sisters of the Frater...y, a new boys' school for one year, the worst of her life:
' For an entire year I hardly received pay. I was asked to do kitchen, supervise the boys. Run errands. Twenty mouths to feed, at least! There were 15 students; a new structure was being founded. The priest, secretary of the priory would pay cold cash, 1000 francs/month. Every month, in his office. So basically $400...for 24/7.'
[Ed. This is an important distinction about the term VOLUNTEERING. True volunteers can show up at an institute, and choose what they want to do, when they want to do it, when to leave, and exit within a few minutes notice, get a free meal out of charity, etc.  But in this particular case, Miss G. was given work to do.  Oh yes! the neoSSP say this was all volunteering. The letter of the law here is twisted.  If this was reported to the employment bureau, this case would be very suspect of illegal work practice. 


ENTERPRISES

Most of the money from the SSPX is managed by the various associations. But we also identified 13 peripheral companies at the 'cult' association. They are all domiciled at the headquarters of the Fraternité, in the mansion of 11 rue Cluseret, in Suresnes.

At their head are the main leaders of the FFSPX: the one responsible for the Financial of the district of France, Fr.Vincent Quilton. The assistant to the superior,  Fr. Loic Duverger. And the abbot Emeric Baudot, general economical of the parent company, in Switzerland. These companies include two LLCs for the sale and publishing of Lefebvrist books. But above all, a construction company, five real estate companies for the rental and management of property and a company Immobilière Familiale (SIF). Not to mention the three real estate programme support companies. In all, ten companies that make the Fraternité Saint-Pie-X a respectable real estate developer. In 2017, one of these six companies, the Family Real Estate Company [Societe Immobiliere Familiale ](SIF), alone made a profit of EUR 8.595 million.

(1) The first names and certain biographical elements have been modified at the request of these former faithful in order to guarantee their anonymity. They keep relatives in the Brotherhood and fear that they will suffer reprisals.