I'm not sure of the reaction of the Kelantanese Buddhists but I am in the opinion that this is not an issue at all.
Buddhism has been a religion of tolerence due to its emphasis on Metta (loving-kindness), Panna (Wisdom) and its universal feature inclined towards non-attachment.
Now if the state government of Kelantan is moving towards Islamizing the state architechture,it is not an issue. There is nowhere in the Tipitaka that states all temples built in the name of 'Buddhism' must have 'Buddhist features'.
Thai Buddhist Wats have been incorporating Hindu elements in its architechture for ages without any much hoohah. Islamic architechture can be another enriching feature to Kelantanese future temples.
I can also see no harm in following the state directive disallowing the display of religious icons clearly in the open. Buddhism, after all began without images. Images were Greeco Buddhist innovation and it spread like wild fire throughout the Buddhist world since it was first created. Buddha images,if the temple wants to have it,can be displayed within the temple premises for devotional purposes. Examplirary forest monks like the late Ajahn Buddhadassa never had any Buddha images in his practice centre. All he had was the Patimokha,that's it.
Having Metta, Buddhists should always be sensitive to the needs of others. Having Panna, Buddhists should weigh the wieght of this issue,is it harming Buddhism,or it's stepping on our ego? Contemplating on non-attachment, one can clearly see this whole issue is but worldly.