Dear aposiopetic,
In the French, it reads, "Il faudra faire admettre aux autorités romaines..."
It's been a lot of years since I took French, but "faudra" is one of the future tenses of a verb that translates as "to be necessary" or "must." "Faire" is "to do," or when combined with other verbs, it can mean "is" (As in, "Il fait chaud," "It is hot," literally, "It does hot."), or also translates at times, "to make [something happen]," or "to cause," when used in conjunction with another verb, as it is here, with "admettre." "Admettre" is the verb "to admit."
So, I'd string it together as roughly, "It is necessary to make [the Roman authorities] admit..."
I think that to translate it as "force" might be a little strong, but there may be idiomatic reasons for it of which I'm blithely unaware. But I think it's reasonable to say "to make admit."
sitetest
I will paste the final paragraph below:
Il faudra faire admettre aux autorités romaines que nous ne pouvons suivre sans de sérieuses restrictions l’interprétation que l’on donne du concile et l’œcuménisme tel qu’il est pratiqué. Au fond, ce que nous espérons, c’est de faire comprendre un jour la raison d’être de la Tradition.
Here is how I would translate it:
It is necessary to get the Roman authorities to admit that we cannot follow without serious restrictions the interpretation given the council or ecumenism as practiced. Beneath it all what we hope is someday to make understood Tradition's raison d'etre.
If I were to regard this as merely a restatement of a general opposition to notions such as those expressed in Dei Verbum 8 and Sacrosanctum Concilium 21, would I be far off?