In those examples, it does not matter.
Conceivably you could have a clause which is ambiguous in respect of the time at which something has to be done, and so the tense of words would be important. A court will try to give effect to the bargain made between the parties as (usually) evidenced by the words used in their written agreement; at times this can boil down to judges picking over words with a fine tooth comb looking for clues, e.g. Coulls v Bagot's Executor and Trustee Co.
Note that your second example is not about tense, it is about active vs passive voice. Passive voice can be ambiguous (e.g. 'any defect in the vehicle will be repaired within 14 days' -- who is liable to do the repairs?) and for that reason should be instinctively avoided, but in this example it does not matter.
Returning to tense, contracts will often be written in a common combination of tenses:
- warranties (in the sense of a guarantee that a fact is true at the time the contract is formed) are written in the past tense, e.g. 'The vendor obtained a roadworthy certificate for the car', or in the present tense, e.g. 'The vendor warrants that the car had a roadworthy certificate';
- executed promises are written in the past tense, e.g. 'The purchaser has paid a deposit of $10,000';
- executory promises are written in the future tense, e.g. 'The vendor will transfer title to the purchaser on such-and-such date';