“表明心迹”可以翻译为 "express one's true feelings/intentions" 或 "declare one's inner thoughts/sentiments"。
"express one's true feelings/intentions"：侧重于直接、真诚地表达内心的情感或意图。
"declare one's inner thoughts/sentiments"：更强调公开或郑重地宣布内心的想法或情感。
根据具体语境，可以选择更贴切的翻译。例如：
He finally expressed his true feelings to her.（他终于向她表明了心迹。）
In his letter, he declared his inner thoughts about their relationship.（在他的信中，他表明了对他们关系的真实想法。）