I checked the sentences that include “magna” which Carolus gave me.
But I couldn’t decide if there was a use of “magna” as meaning “things of great time (things that need or have cost a great amount of time)”.
But thank you.
Below is just an evidence that I examined the sentences Carolus gave me.
As for the use of “magna” as a neuter noun in the plural, that might be possible. I did a full-text search for “magna” as a neuter noun (finding nom. and acc. plural) in the Latin Library-texts of Livy’s Ab urbe condita and Caesar’s De bello Gallico. I found two occurrences that might fit the bill:
Livy, Book II: “Quattuor et uiginti lictores apparere consulibus et eos ipsos plebis homines; nihil contemptius neque infirmius, si sint qui contemnant; sibi quemque ea magna atque horrenda facere.”
(This magna is not of time.)
Livy, Book IV: “Desineret (he should have stopped) ergo mirari cur nemo de commodis plebis (for the profit of, without injury to the people) ageret; eo impendi laborem ac periculum unde emolumentum atque honos speretur; nihil non adgressuros homines si magna ( ) conatis (to the ones who have tried to achieve) magna praemia proponantur”
(This magna may be of importance or of time)
Livy, Book XXXVII: “Ea, quae legato magna ad pacem impetrandam (to be achieved) uidebantur, parua Romanis uisa” (although this example is not strictly what you’re looking for)
(This magna may be of importance or of time.)
Livy, Book ??: “Potiemur (we will possess + abl.) praeterea cum (firstly) pulcherrima opulentissimaque urbe tum (then next) opportunissima portu egregio (good port) unde (then after) terra marique quae belli usus poscunt (require that) suppeditentur (should be supplied); quae (urbs and portus and terra and mare) cum (after) magna ( ) ipsi habebimus tum (then) dempserimus (we will have snatched) hostibus multo maiora.” (not sure about this one)
(This magna is not of time.)
Livy, Book XXXIII: “Adiecta etiam illa uox, bono animo esse regem ut iuberet (was commanding), quae maxime Aetolos offendit iam tumentes (excited) querentesque (complaining) mutatum (has changed) uictoria imperatorem: ante pugnam omnia magna paruaque (matters of great and small value, importance) communicare (to share) cum sociis solitum (he was accustomed to), nunc omnium expertes consiliorum esse, suo ipsum arbitrio (decision) cuncta agere” (not sure abut this one either)
(This magna is not of time.)(This magna is of importance.)
Livy, “Ab urbe condita”, Book I: “Namque Proculus Iulius, sollicita (disturbed) civitate desiderio (desire / petition / need) regis et infensa (hostile) patribus, gravis, ut traditur, quamuis magnae rei auctor in contionem prodit.”
(This mangae is not of time.) (This magna is of importance.)
Livy, Book III: “In exercitu Romano cum duo consules essent potestate pari, quod saluberrimum in administratione magnarum rerum est, summa imperii concedente Agrippa penes collegam erat”
(This magna is of importance.)
Livy, Book XXV: “Rem se ait magnam incohasse, ad quam perficiendam ipsius Gracchi opera opus esse”
(This magnam may be of importance or of time.)
Livy, Book XXXI: “Quod si tantum militum Romanorum fuisset ut et Chalcis teneri et non deseri (to be forsaken) praesidium Athenarum potuisset, magna res principio statim belli, Chalcis et Euripus adempta (snatched away) regi (from the king) forent”
(This magna is not of time.) (This magna is of importance.)
All in all, even “magna” is used fairly seldom. Of course I checked only Livy (a few occurrences) and Caesar (none). One probably could check Cicero, but there a far too many files to do that quickly. I hope that this helps you.
Vale,
Carolus Raeticus