les sommes que ce dernier sera amené à avancer de ce fait pour le compte du locataire > the sums that the former (Lessor/landlord) shall have cause to advance (or prepay or pay in advance), as a result, on behalf of the Lessee/Tenant.


There is a mistake with "ce dernier", it should be "le premier", as the Lessor (landlord) is mentioned first.




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Note added at 30 mins (2022-07-19 14:08:08 GMT)
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amener à - have cause to, have to

https://www.wordreference.com/fren/amener
amener vtr (avoir pour conséquence) cause⇒ vtr
bring⇒ vtr
bring about, lead to vtr phrasal sep

Two examples from the KudoZ records regarding "amené à", both with answers that are basically good translations:

https://www.proz.com/kudoz/french-to-english/general-convers...

https://www.proz.com/personal-glossaries/entry/12110455-a-ét...

I like "called upon to".



To advance: https://www.merriam-webster.com/dictionary/advance (Merriam-Webster is the leading dictionary of American English.

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Note added at 35 mins (2022-07-19 14:12:52 GMT)
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The Lessor (landlord) is the "preneur" and is mentioned first in this clause, Clause 15, so you can refer to the "preneur" using the words "the former" (the party mentioned first), or using the word you have chosen for that party, i.e. Lessor/landlord.

The word "landlord" is probably better.

Hope this helps.

....the sums that the latter shall acordinly be required to pay in advance on behalf of the tenant.

It can be expressed much more simply than the previous answers.

"...will reimburse the owner... all sums that it prepays on the tenant's behalf."