Well, without having read the 'Kanzen Kaihi Healer no Kiseki English Light Novel', it's hard to say precisely. However, given that it has 'healer' in the title, it could center around a healer character who has some sort of special power or mission. Maybe the healer is in a world full of magic and has to overcome various challenges to achieve a certain 'kiseki' which could mean miracle or great accomplishment in Japanese. The 'kanzen kaihi' part might refer to some form of perfect evasion or protection related to the healer's abilities.
One tip is to build a good vocabulary in both Visayan and English. This helps you find the most accurate equivalents. Another is to study the cultural nuances of Visayan. For example, certain traditions or beliefs in Visayan might need special handling in translation. Also, don't be too literal. For instance, if there's a Visayan expression that's very metaphorical, find an English metaphor that conveys a similar meaning.