He/She/It has designed. ... You/We/They have designed. Present Perfect Continuous Tense. He/She/It has been designing.

Is designed or has been designed?

"Was designed" is definitely correct. The action of designing is complete because you are now working on the design. "Has been designed" is probably correct as well, but it sounds too formal. If you said, "and it has recently been designed..." it would make more sense to use the past perfect.

Has been become tense?

It's because typical verbs have same past and past participle forms. But, become is an irregular verb, became is past tense and become is past participle. "to become" is irregular and the author used it wrong. He had to use "become" because it is the third form (past participle) which is needed.