lets get something clear:

do u already possess an engineering diploma, or applying FOR an engineering diploma?

a. if u already have an engineering diploma:

they wont so much look into ur SPM other than to justify the grades and make sure u qualify for the minimum requirements. in any applications, they will always look for the latest qualifications.

b. if u r applying for an engineering diploma:

well, u can, but it'll be harder. priority will always be given to students with science background, but it doesnt mean they will throw ur application out the window.

PTPTN does not give out loans to unaccredited courses. there's no other way around it, atleast not that i know of.

what do u mean by achieving minimum standards of LAN? it's either the course is accredited, or not. that's what matters to PTPTN. if it is accredited, regardless of minimum or outstanding, PTPTN WILL offer the loan to prospective students.

do check on the course accreditation at LAN's website. or just put the name of the course and also the university u're applying here, someone might be able to give a different advice.

What is your diploma course name? It is hard for us to help you if you are unwilling to tell us. Without that course name, we just merely can tell you what we know.

Your diploma is under PTPTN accreditated list. So nothing to be worried about. Your intended degree programs are also under PTPTN loan scheme. As for LAN, nothing to worries. If you works in private sector, most of them will not even bothered to ask.